屋外|おくがいokugai[2]nakadaka (mid-high)

1. no-adjectiveoutdoors; outside
   彼かれらは屋外おくがいスポーツに熱心ねっしんである。↗

   They are keen on outdoor sports.

• Synonym露天ろてんNeutralRefers to open-air, roofless spots, as in 「露天風呂」; it highlights that the facility itself has no roof, rather than simply being outside the building.
• Synonym野外やがいNeutralCovers the outdoors in natural surroundings — fields, open country — as in 「野外活動」 or 「野外コンサート」; the emphasis is on nature, not just outside a building.
• Synonym戸外こがいWrittenA written/formal word for outside the door or house; basically synonymous with 「屋外」 but more literary.
• Synonym室外しつがいNeutralMeans outside the room, as in 「室外機」; it is relative to a room, while 「屋外」 is relative to the building as a whole.
• RelatedおんもCasualBaby talk for outside, as in 「おんもに行こう」; used by small children or when speaking to them. In ordinary contexts say 「外」.
• Related野天のてんWrittenA written word for the open air with no roof or walls; rare today — in everyday speech 「露天」 is the normal choice.
• Antonym屋内おくないNeutralThe antonym of 「屋外」: inside a building, as in 「屋内プール」.
• Antonym室内しつないNeutralMeans inside a room, as opposed to the outside, as in 「室内で遊ぶ」.

Default to 「屋外」 for outside a building (「屋外プール」); 「野外」 suits natural settings, 「露天」 roofless facilities, 「室外」 outside a room (「室外機」). Opposites: 「屋内」, 「室内」. 「おんも」 is childish talk; 「戸外」 and 「野天」 are written-style, the latter now rare.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 建物たてものの外そと。戸外こがい。