戸外|こがいkogai[1]atamadaka (head-high)

1. no-adjectiveopen air; outdoors; outside
   その日ひは戸外こがいで過すごした。↗

   We spent the day in the open air.

• Synonym屋外おくがいNeutralThe standard, most common word for outside a building; interchangeable with 「戸外」, which sounds slightly more written.
• Synonym野外やがいNeutralOpen country or the outskirts, but also outdoors in general, as in 「野外コンサート」; carries a sense of nature and the countryside.
• Synonym露天ろてんNeutralUnder the open sky with no roof, as in 「露天風呂」 and 「露天商」; stresses exposure to wind and rain.
• Synonym表おもてNeutralThe area outside the front of a house, as in 「表で遊ぶ」; also means the surface or front of things.
• Synonym室外しつがいWrittenWritten word for outside a room or building, the counterpart of 「室内」; 「戸外」 is outside the home.
• 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.
• Related野天のてんWrittenWritten style for a spot with no roof or walls, stressing that nothing covers you overhead. Rare in modern usage.
• Antonym室内しつないNeutralInside a room; the usual antonym, paired with 「屋外」 and 「戸外」. The most common word for indoors.
• Antonym戸内WrittenWritten antonym: inside the house. The direct opposite of 「戸外」, but much less used.

For outdoors in general, 「屋外」 is the everyday choice; 「戸外」 is a slightly more written alternative. Use 「野外」 for open country, 「露天」 for spots with no roof, and remember the antonym is 「室内」.

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

1. 家いえの外そと。屋外おくがい。