| 空 | から | emptiness; being empty; not carrying anything; unburdened | n5 |
| 空気 | くうき | air; atmosphere; mood; situation | n4 |
| 空間 | くうかん | space; room; airspace | n2 |
| 空想 | くうそう | daydream; fantasy; fancy; vision | n2 |
| 空港 | くうこう | airport | n5 |
| 空中 | くうちゅう | (in) the air; midair; sky | n1 |
| 青空 | あおぞら | blue sky | n3 |
| 空手 | からて | karate; being empty-handed; having nothing in one's hands | |
| 空く | すく | to become less crowded; to thin out; to get empty; to be hungry | n4 |
| 空しい | むなしい | empty; void; vacant; vain | n1 |
| 空虚 | くうきょ | emptiness; hollowness; vacancy; void | n1 |
| 大空 | おおぞら | wide open sky; the blue; heavens; firmament | n3 |
| 空地 | くうち | vacant land; unoccupied ground; empty lot | |
| 航空 | こうくう | aviation; flying | n2 |
| 空腹 | くうふく | empty stomach; hunger | n1 |
| 空洞 | くうどう | cavity; hollow; cave; cavern | n2 |
| 航空機 | こうくうき | aircraft | n2 |
| 星空 | ほしぞら | starry sky | n1 |
| 虚空 | こくう | empty space; empty sky | |
| 架空 | かくう | fictitious; imaginary; fanciful; fabricated | n1 |
| 夜空 | よぞら | night sky | n2 |
| 空襲 | くうしゅう | air-raid | |
| 上空 | じょうくう | sky; the skies; high-altitude sky; upper air | n3 |
| 真空 | しんくう | vacuum; absolute void; complete vacuity | |
| 中空 | ちゅうくう | hollow; mid-air; air; sky | |
| 空家 | あきや | vacant house; unoccupied house | n3 |
| 空ける | あける | to open (a door, etc.); to unwrap (e.g. parcel, package); to unlock; to open (for business, etc.) | n5 |
| 空っぽ | からっぽ | empty; vacant; hollow | n1 |
| 天空 | てんくう | sky; air; ether; firmament | |
| 空白 | くうはく | blank space (in a document); blank; void; gap | n1 |
| 上の空 | うわのそら | inattention; absent-mindedness | n1 |
| 航空券 | こうくうけん | airline ticket; plane ticket; air ticket | n1 |
| 空手道 | からてどう | the way of karate; karate | |
| 寒空 | さむぞら | wintry sky; cold weather (in winter); wintry weather | |
| 空き | あき | space; room; gap; emptiness | n3 |
| 蒼空 | そうくう | blue sky | |
| 空模様 | そらもよう | look of the sky (esp. of bad weather); weather; course (of events); situation | |
| 夕空 | ゆうぞら | evening sky; twilight sky | |
| 空席 | くうせき | empty seat; unoccupied seat; vacancy; vacant post | n3 |
| 空似 | そらに | accidental resemblance | |
| 空色 | そらいろ | sky blue | |
| 空々しい | そらぞらしい | false; hypocritical | |
| 空咳 | からせき | dry cough; hacking cough; intentional cough (e.g. to get someone's attention) | |
| 空堀 | からぼり | dry moat | |
| 空論 | くうろん | abstract or impracticable theory | n1 |
| 空車 | くうしゃ | empty conveyance; empty taxi; free taxi; having spaces available (of a parking lot) | |
| 空疎 | くうそ | empty (e.g. argument); insubstantial; hollow; fruitless | n1 |
| 空軍 | くうぐん | air force | |
| 防空 | ぼうくう | air defense; air defence | |
| 空前 | くうぜん | unprecedented; record-breaking | |
| 空頼み | そらだのみ | vain hope | |
| 空き家 | あきや | vacant house; unoccupied house | n3 |
| 空々 | くうくう | empty; vacant; void | |
| 時空 | じくう | space-time; spacetime | |
| 空漠 | くうばく | vast; boundless; vague | |
| 空耳 | そらみみ | mishearing; (feigned) deafness; homophonic translation of song lyrics for comic effect | |
| 空費 | くうひ | waste; wastefulness | |
| 冬空 | ふゆぞら | winter sky | |
| 滑空 | かっくう | gliding (through the air) | |
| 秋空 | あきぞら | autumn sky; clear blue autumnal sky | |
| 防空壕 | ぼうくうごう | air-raid shelter; bomb shelter | |
| 孫悟空 | そんごくう | Sun Wukong (character in the classic Chinese novel Journey to the West); Monkey King; Son Goku (Dragon Ball) | |
| 碧空 | へきくう | blue sky; azure sky | |
| 空室 | くうしつ | vacant room; vacancy; unoccupied room; empty room | |
| 空恐ろしい | そらおそろしい | apprehensive; vaguely fearful; gloomy (about the future); somewhat alarmed | |
| 空隙 | くうげき | vacant space; aperture; gap; opening | |
| 青空文庫 | あおぞらぶんこ | Aozora Bunko (digital library of Japanese public-domain works) | |
| 空弁 | そらべん | boxed lunch sold at airports | |
| 空とぼける | そらとぼける | to feign ignorance; to play dumb | |
| 航空会社 | こうくうがいしゃ | airline company | |
| 空調 | くうちょう | air conditioning | |
| 空気感 | くうきかん | atmosphere (esp. of a place or person); mood; vibe; ambience | |
| 空嘯く | そらうそぶく | to feign ignorance; to pretend not to know; to feign indifference; to assume a nonchalant air | |
| 空挺 | くうてい | airborne (troops, operation, etc.) | |
| 曇り空 | くもりぞら | cloudy sky; overcast sky | |
| 空巣 | あきす | empty nest; empty house; empty home; burglary (of an empty house) | |
| 国際空港 | こくさいくうこう | international airport | |
| 身空 | みそら | body; one's fortune | |
| 雨空 | あまぞら | rainy sky; sky as it looks when it is about to rain; threatening sky | |
| 空き地 | あきち | vacant land; unoccupied ground; empty lot; empty point | n3 |
| 空合 | そらあい | weather; course of events | |
| 空き状況 | あきじょうきょう | availability (of rooms, parking, appointments, etc.) | |
| 雪空 | ゆきぞら | snow-laden sky | |
| 空茶 | からちゃ | tea served without sweets | |
| 航空書簡 | こうくうしょかん | aerogramme; air letter | |
| 空ろ | うつろ | cavity; hollow; void; hollow (voice, smile, etc.) | n3 |
| 空身 | からみ | traveling alone and with little luggage (travelling) | |
| 空母 | くうぼ | aircraft carrier | |
| 空言 | そらごと | falsehood; lie | |
| 低空 | ていくう | low altitude; low sky | |
| 空前絶後 | くうぜんぜつご | (so marvelous or horrible that it may be) the first and probably the last | |
| 空転 | くうてん | racing (of an engine); idling; going in circles (of an argument, discussion, etc.); spinning one's wheels | |
| 宇宙空間 | うちゅうくうかん | (outer) space | |
| 空挺部隊 | くうていぶたい | airborne troops; paratroops | |
| 高空 | こうくう | high altitude | n2 |
| 空っ風 | からっかぜ | cold, strong, dry wind | |
| 空蝉 | うつせみ | this fleeting world; this transient life; this world; one's current body | |
| うわの空 | うわのそら | inattention; absent-mindedness | n1 |
| 空威張り | からいばり | bluffing; bluster; bravado | |
| 空寂 | くうじゃく | complete emptiness (i.e. as a denial of the inherent existence of all things); nirvana (where this emptiness is realized); quiet and lonely | |
| 空爆 | くうばく | aerial bombing | |
| 空砲 | くうほう | empty gun; gun loaded with blanks; firing a blank | |
| 空腹時 | くうふくじ | fasting | |
| 空路 | くうろ | air route; air lane; by air; by plane | |
| 空欄 | くうらん | blank column; blank space | n1 |
| 空文 | くうぶん | dead letter | |
| 空元気 | からげんき | putting on a brave face; put-on cheeriness; pretending one is fine; show of courage | |
| 空振り | からぶり | swing and a miss; (punching and) failing to make contact; (ending in) failure; fruitless effort | |
| 空中写真 | くうちゅうしゃしん | aerial photograph | |
| 空拳 | くうけん | with bare hands; with or from nothing | |
| 空間的 | くうかんてき | spatial; space-like | |
| 空気圧 | くうきあつ | air pressure (of tires) | |
| 空谷 | くうこく | lonely or uninhabited valley | |
| 空港線 | くうこうせん | Airport Line; Kūkō Line | |
| 航空便 | こうくうびん | airmail; air mail; air service; air transport (of goods) | |
| 色即是空 | しきそくぜくう | form is emptiness; matter is void; all is vanity | |
| 空理空論 | くうりくうろん | impractical theory; academic discussion; doctrinairism | |
| 対空 | たいくう | anti-aircraft; antiaircraft | |
| 空力 | くうりき | aerodynamics | |
| 空き腹 | すきはら | empty stomach; hunger | |
| 空回り | からまわり | racing (of an engine); idling; spinning (without grabbing; of wheels); going round in circles (of an argument, discussion, etc.) | |
| 関西空港線 | かんさいくうこうせん | Kansai Airport Line | |
| 空空 | くうくう | empty; vacant; void | |
| 空挺兵 | くうていへい | paratrooper | |
| 徒手空拳 | としゅくうけん | being empty-handed; being penniless; having no capital (for starting a business) | |
| 空き巣 | あきす | empty nest; empty house; empty home; burglary (of an empty house) | |
| 空気枕 | くうきまくら | air cushion | |
| 空寝 | そらね | feigned sleep; playing possum | |
| 空かす | すかす | to feel hungry; to get hungry | |
| 空港駅 | くうこうえき | airport (rail) station | |
| 航空隊 | こうくうたい | flying corps | |
| 虚空蔵 | こくうぞう | Akasagarbha (bodhisattva); the Receptacle of Void | |
| がら空き | がらあき | almost completely empty; virtually empty; inadequately defended; undefended | |
| 空名 | くうめい | empty name; false reputation | |
| 空荷 | からに | lacking cargo; in ballast | |
| 美空 | みそら | beautiful sky | |
| 生活空間 | せいかつくうかん | living space | |
| 空理 | くうり | empty theory; impracticable theory | |
| 空際 | くうさい | horizon; point where the sky meets the earth | |
| 赤手空拳 | せきしゅくうけん | barehanded; having no wealth or position to rely on (aside from one's own resourcefulness) (when embarking on something) | |
| 空馬 | からうま | unburdened horse | |
| 航空自衛隊 | こうくうじえいたい | Japan Air Self-Defense Force; JASDF | |
| 空惚ける | そらとぼける | to feign ignorance; to play dumb | |
| 空挺作戦 | くうていさくせん | airborne operation | |
| 虚空蔵菩薩 | こくうぞうぼさつ | Akasagarbha (bodhisattva) | |
| 空涙 | そらなみだ | crocodile tears | |
| 空中庭園 | くうちゅうていえん | hanging garden; hanging gardens | |
| 空気抵抗 | くうきていこう | air resistance | |
| 空位 | くうい | vacant post; vacancy; post in name only | |
| 空売り | からうり | short selling | |
| 空気電池 | くうきでんち | air cell; air battery | |
| 仮空 | かくう | fictitious; imaginary; fanciful; fabricated | n1 |
| 空木 | うつぎ | deutzia (Deutzia crenata) | |
| 照空灯 | しょうくうとう | (anti-aircraft) searchlight | |
| 照空燈 | しょうくうとう | (anti-aircraft) searchlight | |
| 空念仏 | そらねんぶつ | empty words | |
| 空梅雨 | からつゆ | (unusually) dry rainy season | |
| 航空写真 | こうくうしゃしん | aerial photograph | |
| 空道 | くうどう | kūdō (martial art form) | n2 |
| 航空法 | こうくうほう | Civil Aeronautics Law; Aviation Law | |
| 空世辞 | からせじ | flattery; insincere praise; empty compliments | |
| 空挺師団 | くうていしだん | airborne division | |
| 空気抜き | くうきぬき | ventilator | |
| 航空母艦 | こうくうぼかん | aircraft carrier | |
| 空穂 | うつぼ | quiver (cylindrical and worn on the back or hip) | |
| 空閨 | くうけい | lonely, spouseless bedroom; bedroom of a neglected spouse | |
| 空音 | そらね | imitated cry (of an animal); lie | |
| 臨空 | りんくう | airport site; adjacent to airport | |
| 空中戦 | くうちゅうせん | air battle; dog fight; aerial battle | |
| 空飛ぶ | そらとぶ | to fly in the sky | |
| 絵空事 | えそらごと | fabrication; pipe dream | |
| 陸海空 | りくかいくう | land, sea and air; army, navy and air force | |
| 位相空間 | いそうくうかん | phase space; topological space | |
| 空港使用料 | くうこうしようりょう | landing fee | |
| 空孔 | くうこう | (electron) hole; (lattice) vacancy; void | n5 |
| 空き缶 | あきかん | empty can | n4 |
| 空目 | そらめ | thinking one saw something that wasn't actually there; hallucination; pretending not to see; looking the other way | |
| 空手家 | からてか | karate practitioner; karateka | |
| 空腹感 | くうふくかん | feeling of emptiness in the stomach; sensation of hunger | |
| 居住空間 | きょじゅうくうかん | living space | |
| 滞空 | たいくう | staying in the air; remaining airborne | |
| 空域 | くういき | airspace | |
| 空輸 | くうゆ | air transport; air lift; airlift | |
| 空電 | くうでん | static | |
| 空中線 | くうちゅうせん | antenna | |
| 空挺隊 | くうていたい | airborne troops; paratroops | |
| 空笑い | そらわらい | feigned laughter | |
| 空間線量 | くうかんせんりょう | air dose (esp. radioactivity) | |
| 空事 | そらごと | fake; fabrication | |
| 空談 | くうだん | gossip; chatter | |
| 全日空 | ぜんにっくう | All Nippon Airways (abbr); ANA | |
| 制空権 | せいくうけん | control of the air; air supremacy | |
| 大空襲 | だいくうしゅう | major air raid; blitz | |
| 空挺旅団 | くうていりょだん | airborne brigade; parachute brigate | |
| 空気入れ | くうきいれ | air pump; bicycle pump | |
| 航空宇宙 | こうくううちゅう | aerospace | |
| 空圧 | くうあつ | air pressure; pneumatic pressure | |
| 真空管 | しんくうかん | vacuum tube | |
| 空想的 | くうそうてき | imaginary; fantastical; visionary; utopian | |
| 空間内 | くうかんない | inside a space | |
| 空調設備 | くうちょうせつび | air conditioner | |
| 航空輸送 | こうくうゆそう | air transportation; air transport; transport by air | |
| 空洞化 | くうどうか | making hollow; making meaningless; deindustrialization; deindustrialisation | n1 |
| 初空 | はつそら | sky on New Year's morning | |
| 大空間 | だいくうかん | large space | |
| 空手形 | からてがた | fictitious bill; dishonoured bill; bad check; empty promise | |
| 航空戦 | こうくうせん | aerial warfare; air war | |
| 空即是色 | くうそくぜしき | emptiness is form; illusion of the reality of matter | |
| 航空無線 | こうくうむせん | aeronautical radio; aircraft radio | |
| 全日本空輸 | ぜんにっぽんくうゆ | All Nippon Airways | |
| 航空交通管制 | こうくうこうつうかんせい | air traffic control | |
| 司空 | しくう | Minister of Works (Zhou dynasty China) | |
| 異空間 | いくうかん | unusual space; other dimension | |
| 空き間 | あきま | vacancy; room for rent or lease; gap (between two objects); opening | |
| 空中機動 | くうちゅうきどう | air mobile | |
| 航空貨物 | こうくうかもつ | air cargo; air freight | |
| 空屋 | あきや | vacant house; unoccupied house | n3 |
| 夏空 | なつぞら | summer sky; summery weather; clear, blazing summer weather | |
| 空自 | くうじ | Air Self-Defense Force; ASDF | |
| 住空間 | じゅうくうかん | living space | |
| 空手着 | からてぎ | karate gi; karate uniform | |
| 空揚げ | からあげ | deep-frying food lightly coated in flour or potato starch; deep-fried food (esp. chicken) | |
| 空景気 | からげいき | false prosperity; superficial prosperity | |
| 空虚感 | くうきょかん | feeling of emptiness; sense of void | |
| 仮想空間 | かそうくうかん | virtual space (e.g. in computer graphics) | |
| 空気力学 | くうきりきがく | aerodynamics | |
| 空間認識 | くうかんにんしき | space perception; spatial perception; spatial awareness | |
| 東京大空襲 | とうきょうだいくうしゅう | Great Tokyo Air Raid (March 10, 1945) | |
| 空戦 | くうせん | air battle; dogfight | |
| 空豆 | そらまめ | broad bean (Vicia faba); horse bean; fava bean | |
| 大韓航空 | たいかんこうくう | Korean Air; KAL | |
| 空襲警報 | くうしゅうけいほう | air-raid alarm | |
| 絵空ごと | えそらごと | fabrication; pipe dream | |
| 航空力学 | こうくうりきがく | flight dynamics; aerodynamics; aeromechanics | |
| 航空工学 | こうくうこうがく | aeronautical engineering | |
| 空焼き | からやき | applying heat to an empty pan to remove its anti-rust coating; blind-baking; baking a pie crust, tart shell, etc. before adding a filling | |
| 空閑地 | くうかんち | vacant lot or land | |
| 空集合 | くうしゅうごう | empty set | |
| 航空図 | こうくうず | aeronautical chart | |
| 超時空 | ちょうじくう | super-dimensional | |
| 圧縮空気 | あっしゅくくうき | compressed air | |
| 空き容量 | あきようりょう | free space (on a disk) | |
| 防空頭巾 | ぼうくうずきん | air-raid hood | |
| 原子力空母 | げんしりょくくうぼ | nuclear-powered aircraft carrier | |
| 空缶 | あきかん | empty can | n4 |
| 朝空 | あさぞら | morning sky | |
| 空風 | からかぜ | dry wind | |
| 空解け | そらどけ | coming untied | |
| 航空学 | こうくうがく | aeronautics | |
| 色空間 | いろくうかん | colour space; color space | |
| 天空海闊 | てんくうかいかつ | the open sky and the serene sea; as open as the sky and serene as the sea; magnanimous | |
| 机上空論 | きじょうのくうろん | armchair theory; impracticable plan; unworkable idea | |
| 空中投下 | くうちゅうとうか | airdrop; air drop | |
| 空空しい | そらぞらしい | false; hypocritical | |
| 航空戦隊 | こうくうせんたい | air flotilla; air fleet; combat aviation unit of the Imperial Japanese Navy | |
| 護衛空母 | ごえいくうぼ | escort carrier; jeep carrier | |
| 距離空間 | きょりくうかん | metric space | |
| 航空大学校 | こうくうだいがっこう | Civil Aviation College; College of Aeronautics; COA | |
| 空き屋 | あきや | vacant house; unoccupied house | n3 |
| 空夢 | そらゆめ | fabricated dream | |
| 空所 | くうしょ | blank; empty space; gap | |
| 空瓶 | あきびん | empty bottle | |
| 空説 | くうせつ | groundless rumor or story (rumour) | |
| 空賊 | くうぞく | air pirate; air piracy | |
| 空釣 | からづり | fishing without bait | |
| 領空 | りょうくう | territorial airspace | |
| 手空き | てすき | not busy; unengaged; being free; leisure | |
| 時空間 | じくうかん | space-time | |
| 空き店 | あきだな | empty house; vacant house | |
| 空き箱 | からばこ | empty box | |
| 空せき | からせき | dry cough; hacking cough; intentional cough (e.g. to get someone's attention) | |
| 空想家 | くうそうか | dreamer; daydreamer; visionary | |
| 空蒸し | からむし | steaming (of food) | |
| 航空路 | こうくうろ | air route; airway; air lane; air corridor | |
| 低空飛行 | ていくうひこう | low-altitude flying; having consistently poor results (grades, sales, etc.); barely scraping by; being on the verge of failing | |
| 名前空間 | なまえくうかん | namespace | |
| 地下空間 | ちかくうかん | underground space; subterranean space; subterranea | |
| 対空砲火 | たいくうほうか | anti-aircraft fire; flak | |
| 拠点空港 | きょてんくうこう | hub airport | |
| 空っ下手 | からっぺた | utterly lacking (in ability); hopeless; useless; poor | |
| 空気伝染 | くうきでんせん | air-borne infection | |
| 空気調整 | くうきちょうせい | air conditioning | |
| 空軍大尉 | くうぐんたいい | air force captain | |
| 航空基地 | こうくうきち | air base | |
| 航空管制 | こうくうかんせい | air traffic control; ATC | |
| 航空郵便 | こうくうゆうびん | airmail; air mail | |
| 陸海空軍 | りくかいくうぐん | army, navy and air force; land, sea and air forces | |
| 地水火風空 | ちすいかふうくう | earth, water, fire, wind and void (the five elements) | |
| 空冷 | くうれい | air cooling | |
| 空包 | くうほう | blank cartridge; blank ammunition; blank | |
| 空株 | からかぶ | fictitious stock | |
| 空箱 | からばこ | empty box | |
| 空籤 | からくじ | blank (ticket); unsuccessful lottery ticket | |
| 梅雨空 | つゆぞら | overcast sky in the rainy season | |
| 滑空機 | かっくうき | glider | |
| 空取引 | からとりひき | fictitious transaction; paper transaction | |
| 空押し | からおし | embossing; inkless stamping | |
| 空泣き | そらなき | false or crocodile tears; feigned sadness | |
| 空買い | からがい | buying on margin | |
| 空間性 | くうかんせい | extensity | |
| 空間群 | くうかんぐん | space group | |
| 空風呂 | からぶろ | steam bath; empty bath | |
| 架空請求 | かくうせいきゅう | false invoice; false billing | |
| 海上空港 | かいじょうくうこう | seadrome | |
| 滞空時間 | たいくうじかん | flight duration | |
| 真空包装 | しんくうほうそう | vacuum packaging | |
| 空中浮遊 | くうちゅうふゆう | levitation; floating on air; airborne (e.g. bacteria); aero- | |
| 空中衝突 | くうちゅうしょうとつ | midair collision | |
| 空席待ち | くうせきまち | stand-by (on an airplane) | |
| 空気感染 | くうきかんせん | airborne infection | |
| 空気調和 | くうきちょうわ | air conditioning | |
| 絶対空間 | ぜったいくうかん | absolute space | |
| 都市空間 | としくうかん | urban space | |
| ノースウエスト航空 | ノースウエストこうくう | Northwest Airlines | |
| 制空 | せいくう | mastery of the air | |
| 空佐 | くうさ | (Self Defense Force's Air Force) colonel (defence); lieutenant; major | |
| 空処 | くうしょ | blank; empty space; gap | |
| 空列 | くうれつ | null string | |
| 空振 | くうしん | atmospheric vibration; infrasound (as produced by volcanic activity) | |
| 空様 | そらざま | arching backward; looking up | |
| 空濠 | からぼり | dry moat | |
| 空腸 | くうちょう | jejunum | |
| 空舟 | うつろぶね | utsuro-bune; hollow ship; unidentified craft said to have washed ashore in Ibaraki Prefecture in 1803, sometimes alleged to have been a UFO | |
| 空運 | くううん | air transportation; air transport | |
| 空陸 | くうりく | land and air; land and air forces | |
| 実空間 | じつくうかん | position space (quantum mechanics); real space | |
| 空き室 | あきしつ | vacant room; vacancy; unoccupied room; empty room | |
| 空き枠 | あきわく | open time slot; unoccupied time slot | |
| 空き車 | あきぐるま | empty car; unloaded car | |
| 空くじ | からくじ | blank (ticket); unsuccessful lottery ticket | |
| 空気流 | くうきりゅう | air flow | |
| 空気浴 | くうきよく | air bath | |
| 空気穴 | くうきあな | air vent (hole) | |
| 空相場 | からそうば | fictitious transaction | |
| 空調機 | くうちょうき | air conditioning unit; AC unit; air conditioner | |
| 空返事 | そらへんじ | absentminded response | |
| 米空軍 | べいくうぐん | US Air Force | |
| 航空兵 | こうくうへい | airman; airwoman; aviator | |
| 対空射撃 | たいくうしゃげき | anti-aircraft fire; shooting at an aircraft (from ground or ship) | |
| 潜水空母 | せんすいくうぼ | submarine aircraft carrier | |
| 真空容器 | しんくうようき | vacuum vessel; vacuum chamber | |
| 空になる | からになる | to become empty; to be emptied | |
| 空中散歩 | くうちゅうさんぽ | stroll in the air (e.g. leisurely helicopter, airplane ride) | |
| 空中浮揚 | くうちゅうふよう | levitation | |
| 空中給油 | くうちゅうきゅうゆ | aerial refueling; in-flight refueling | |
| 空中電気 | くうちゅうでんき | atmospheric electricity | |
| 空力性能 | くうりきせいのう | aerodynamic performance | |
| 空気冷却 | くうきれいきゃく | air cooling | |
| 空気機械 | くうききかい | pneumatic machinery | |
| 空白時間 | くうはくじかん | idle time; down time; window period | |
| 空白期間 | くうはくきかん | blank period; window period; interregnum | |
| 空空漠漠 | くうくうばくばく | vast; boundless; wide and empty; vague and hazy | |
| 航空保険 | こうくうほけん | aviation insurance; aerial insurance | |
| 航空医学 | こうくういがく | aviation medicine | |
| 航空灯台 | こうくうとうだい | aeronautical beacon | |
| 航空燃料 | こうくうねんりょう | aviation fuel | |
| 航空燈台 | こうくうとうだい | aeronautical beacon | |
| 電脳空間 | でんのうくうかん | cyberspace | |
| 宮崎空港線 | みやざきくうこうせん | Miyazaki Airport Line | |
| 時空連続体 | じくうれんぞくたい | space-time continuum | |
| 無人航空機 | むじんこうくうき | unmanned aerial vehicle (UAV); drone | |
| 脊髄空洞症 | せきずいくうどうしょう | syringomyelia | |
| 航空発動機 | こうくうはつどうき | aircraft engine | |
| 航空發動機 | こうくうはつどうき | aircraft engine | |
| 陸軍航空隊 | りくぐんこうくうたい | army aviation | |
| 新東京国際空港公団 | しんとうきょうこくさいくうこうこうだん | New Tokyo International Airport Authority | |
| 空劫 | くうこう | the kalpa of nothingness (the final aeon of the universe) | n5 |
| 空桶 | からおけ | empty bucket; karaoke | n4 |
| 空オケ | カラオケ | karaoke | n4 |
| 空きカン | あきかん | empty can | n4 |
| 空素 | からす | dealt hand containing only 1-point cards (scoring combination) | n3 |
| 空きや | あきや | vacant house; unoccupied house | n3 |
| 公空 | こうくう | international airspace; international space | n2 |
| 空曹 | くうそう | noncommissioned officer of the Japanese Air Self Defense Forces (Defence) | n2 |
| 空相 | くうそう | the empty nature of all things | n2 |
| 空胴 | くうどう | cavity; hollow; cave; cavern | n2 |
| 空走 | くうそう | moving while the brakes are applied but before they start to slow the vehicle down | n2 |
| 空ふく | くうふく | empty stomach; hunger | n1 |
| 宙空 | ちゅうくう | (in) the air; midair; sky; (empty) space | |
| 成空 | せいくう | come to nothingness | |
| 空け | うつけ | absentmindedness; dreaminess; carelessness; fool | |
| 空で | そらで | off the top of one's head; from thin air; from memory | |
| 空メ | からメ | blank email (e.g. for signing up to an email list) | |
| 空吹 | うそふき | usofuki; kyogen mask with bulging eyes and pursed lips (as if whistling) | |
| 空嘔 | からえずき | retching; vomiturition | |
| 空将 | くうしょう | (Self Defense Force's Air Force) general (defence); lieutenant; major | |
| 空尉 | くうい | (Self Defense Force's Air Force) captain (defence); lieutenant | |
| 空店 | あきだな | empty house; vacant house | |
| 空引 | そらびき | type of loom used in olden times; loom; traditional loom | |
| 空揚 | からあげ | deep-frying food lightly coated in flour or potato starch; deep-fried food (esp. chicken) | |
| 空撮 | くうさつ | aerial photography | |
| 空方 | そらざま | arching backward; looking up | |
| 空書 | そらがき | air writing; spacial calligraphy (artform) | |
| 空札 | からふだ | dead card (comp. karuta); cards that are not present at the start of the match | |
| 空炷 | そらだき | burning incense without making its source obvious; pleasant smell coming from an unknown location | |
| 空焚 | からだき | heating a vessel without water in it; heating an empty pan, kettle, boiler, bathtub, etc. | |
| 空然 | くうぜん | vacant and unthinking; something that should be there is not | |
| 空焼 | からやき | applying heat to an empty pan to remove its anti-rust coating; blind-baking; baking a pie crust, tart shell, etc. before adding a filling | |
| 空狐 | くうこ | fox with supernatural powers | |
| 空発 | くうはつ | exploding without destroying the target; going off (of a gun) before taking aim | |
| 空穴 | からけつ | flat or stone broke | |
| 空箸 | そらばし | touching a food with one's chopsticks, then removing them without taking it (a breach of etiquette) | |
| 空聴 | からテン | tenpai with all potential winning tiles visible on table (impossible to win) | |
| 空胞 | くうほう | vacuole (esp. in an animal cell) | |
| 空薫 | そらだき | burning incense without making its source obvious; pleasant smell coming from an unknown location | |
| 空行 | くうぎょう | blank line | |
| 空諦 | くうたい | truth of emptiness (holding that all things are void) | |
| 空震 | くうしん | atmospheric vibration; infrasound (as produced by volcanic activity) | |
| 空鼾 | そらいびき | pretending to snore; sham snore | |
| 中空壁 | ちゅうくうかべ | hollow walls | |
| 亜空間 | あくうかん | subspace (in science fiction); space free from the laws of physics | |
| 准空尉 | じゅんくうい | warrant officer (JASDF) | |
| 地対空 | ちたいくう | surface-to-air | |
| 夕焼空 | ゆうやけぞら | sky aglow with the setting sun; sky at sunset; red sky | |
| 大真空 | だいしんくう | Daishinku Corporation | |
| 姫空木 | ひめうつぎ | slender deutzia (Deutzia gracilis) | |
| 対空砲 | たいくうほう | anti-aircraft gun; antiaircraft artillery | |
| 居空き | いあき | burglary (while occupants are present); burglar (of a house where occupants are present) | |
| 旅の空 | たびのそら | away from home; while travelling | |
| 暁の空 | あかつきのそら | dawning sky | |
| 毒空木 | どくうつぎ | Coriaria japonica (species of shrub) | |
| 真空帯 | しんくうたい | air pocket | |
| 真空槽 | しんくうそう | vacuum column | |
| 秋の空 | あきのそら | clear autumn sky | |
| 空き壜 | あきびん | empty bottle | |
| 空き日 | あきび | day that something (e.g. a venue) is available to use; day that one is available | |
| 空き樽 | あきだる | empty barrel | |
| 空き殻 | あきがら | empty shell | |
| 空き瓶 | あきびん | empty bottle | |
| 空け者 | うつけもの | fool; blockhead; idiot; dunce | |
| 空しく | むなしく | in vain; to no purpose; fruitlessly | |
| 空だき | からだき | heating a vessel without water in it; heating an empty pan, kettle, boiler, bathtub, etc. | |
| 空っ穴 | からっけつ | flat broke; stone broke; penniless | |
| 空の便 | そらのびん | flight (plane) | |
| 空の旅 | そらのたび | air travel; air trip | |
| 空の煙 | そらのけぶり | crematorium smoke rising in the sky | |
| 空ぶり | からぶり | swing and a miss; (punching and) failing to make contact; (ending in) failure; fruitless effort | |
| 空クジ | からくじ | blank (ticket); unsuccessful lottery ticket | |
| 空コン | からコン | empty (e.g. intermodal containers in the transport industry) | |
| 空テン | からテン | tenpai with all potential winning tiles visible on table (impossible to win) | |
| 空下手 | からへた | utterly lacking (in ability); hopeless; useless; poor | |
| 空中権 | くうちゅうけん | air rights | |
| 空乏層 | くうぼうそう | depletion layer (of transistor) | |
| 空也餅 | くうやもち | chunky mochi made with half-polished rice, stuffed with red bean paste | |
| 空写し | からうつし | clicking the shutter of a camera without taking a picture (because no film is loaded, or in order to advance the film) | |
| 空冷式 | くうれいしき | air-cooled | |
| 空出張 | からしゅっちょう | fictitious business trip; fraudulent claim of expenses for a nonexistent business trip | |
| 空力音 | くうりきおん | aerodynamic sound; aerodynamic noise | |
| 空合い | そらあい | weather; course of events | |
| 空士長 | くうしちょう | airman first class (JASDF) | |
| 空対地 | くうたいち | air-to-surface | |
| 空対空 | くうたいくう | air-to-air | |
| 空将補 | くうしょうほ | major general (JASDF) | |
| 空屋敷 | あきやしき | empty residence; empty estate; empty lot | |
| 空引き | そらびき | type of loom used in olden times; loom; traditional loom | |
| 空心菜 | くうしんさい | Chinese water spinach (Ipomoea aquatica); ong choy; kang kong; water morning glory | |
| 空想力 | くうそうりょく | (power of) imagination | |
| 空振る | からぶる | to swing and miss | |
| 空挺堡 | くうていほ | airhead | |
| 空更新 | からこうしん | dummy update; null update | |
| 空書き | そらがき | air writing; spacial calligraphy (artform) | |
| 空曹長 | くうそうちょう | senior master sergeant (JASDF) | |
| 空残業 | からざんぎょう | overtime fraud; reporting false overtime hours | |
| 空気口 | くうきこう | vent | |
| 空気孔 | くうきこう | air pocket; air hole | |
| 空気房 | くうきぼう | auxiliary air bag (balloon, etc.); ballonnet | |
| 空気砲 | くうきほう | air cannon (toy) | |
| 空気袋 | くうきぶくろ | air sac; bladder; air bag; windbag | |
| 空気銃 | くうきじゅう | air gun; air rifle | |
| 空港税 | くうこうぜい | airport-imposed taxes; airport tax | |
| 空炊き | からだき | heating a vessel without water in it; heating an empty pan, kettle, boiler, bathtub, etc. | |
| 空炒り | からいり | light roasting; light toasting; parching | |
| 空焚き | からだき | heating a vessel without water in it; heating an empty pan, kettle, boiler, bathtub, etc. | |
| 空煎り | からいり | light roasting; light toasting; parching | |
| 空燃比 | くうねんひ | air-fuel ratio; AFR | |
| 空状態 | くうじょうたい | empty state; nil state | |
| 空白列 | くうはくれつ | blank sequence | |
| 空白区 | くうはくく | vacant constituency | |
| 空眠り | そらねむり | feigned sleep | |
| 空約束 | からやくそく | empty promise; hollow promise | |
| 空胞化 | くうほうか | vacuolation; vacuolization | |
| 空芯菜 | くうしんさい | Chinese water spinach (Ipomoea aquatica); ong choy; kang kong; water morning glory | |
| 空薫き | そらだき | burning incense without making its source obvious; pleasant smell coming from an unknown location | |
| 空薬莢 | からやっきょう | spent shell casing; empty cartridge | |
| 空覚え | そらおぼえ | learning by heart; memorization; faint memory; vague recollection | |
| 空証文 | そらしょうもん | empty promise | |
| 空論家 | くうろんか | a doctrinaire | |
| 空貸し | からがし | demanding payment for a non-existent loan | |
| 空軍力 | くうぐんりょく | air power | |
| 空軍機 | くうぐんき | air force aircraft | |
| 空部屋 | あきべや | available room (hotel); vacancy; room to let | |
| 空釣り | からづり | fishing without bait | |
| 空間軸 | くうかんじく | spatial axis | |
| 空雀鯛 | そらすずめだい | neon damselfish (Pomacentrus coelestis); heavenly damselfish | |
| 空騒ぎ | からさわぎ | making a fuss (about nothing); brouhaha | |
| 空高い | そらたかい | high in the sky | |
| 空高く | そらたかく | high in the sky | |
| 糊空木 | のりうつぎ | panicled hydrangea (Hydrangea paniculata); peegee hydrangea | |
| 絵空言 | えそらごと | fabrication; pipe dream | |
| 航空病 | こうくうびょう | airsickness | |