indoor

American  

[in-dawr, -dohr] / ˈɪnˌdɔr, -ˌdoʊr /

adjective

1. occurring, used, etc., in a house or building, rather than out of doors.

   indoor games.

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indoor British  

/ ˈɪnˌdɔː /

adjective

1. of, situated in, or appropriate to the inside of a house or other building

   an indoor tennis court

   indoor amusements

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Etymology

Origin of indoor

1705–15; aphetic variant of within-door, originally phrase within ( the ) door, i.e., inside the house

Explanation

Use the adjective indoor to describe something that happens or is used inside a building or house. Your indoor furniture is probably a little fancier than your plastic outdoor furniture. Indoor sports are the ones you play inside, like ping pong and floor hockey — beach volleyball is not an indoor sport. Your indoor voice is likewise the one you use in your house or classroom, a quieter voice than when you holler across a parking lot to your friend in his convertible. Indoor, which has been used since the 18th century, is a shortened form of the phrase within door.

Example Sentences

Never underestimate the joys of a good mattress and flattering indoor lighting.

From MarketWatch • Apr. 17, 2026

“Didn’t have indoor plumbing until I was 15.”

From Los Angeles Times • Apr. 16, 2026

It calls its approach “Return on Air,” or the benefits of clean indoor air, including efficiency, productivity and health.

From Barron's • Apr. 15, 2026

He and his wife, Susan, have taken several Viking cruises in Europe and just bought a home in a Pennsylvania retirement community with an indoor pool and an outdoor pool.

From The Wall Street Journal • Apr. 5, 2026

In the middle of this indoor forest, smack in the center of it all, were two rocking chairs and a small table between them with a small cassette player on it.

From "As Brave As You" by Jason Reynolds

Related Words

• private