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located, done or used inside a building （在）室内的；在户内进行的；在室内用的 an indoor swimming pool 室内游泳池 indoor games 室内游戏 Poor indoor air quality can result in increased risk of asthma and allergies. 室内空气质量差会导致哮喘和过敏的风险增加。
Oxford Collocations DictionaryIndoor is used with these nouns:- arena
- athletics
- court
- …
relating to sports played indoors 室内： 与室内运动有关the world indoor 200 metres champion 室内 200 米赛世界冠军
Word Originearly 18th cent. (superseding earlier within-door): from in (as a preposition) + door. Compare with indoors.