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

Indoor seating is reserved at $25 a head, while the outdoor courtyard is first come, first served.

From The Wall Street Journal • Jun. 11, 2026

Indoor tanning is associated with a 75% increase in melanoma risk.

From Los Angeles Times • May 7, 2026

Great Britain claimed three gold medals in a sensational 28 minutes to make history and achieve the team's best haul at a World Athletics Indoor Championships.

From BBC • Mar. 22, 2026

On Friday, footage emerged of the smouldering and ruined 12,000-seat Azadi Indoor Stadium in Tehran.

From Barron's • Mar. 6, 2026

Indoor sandals and outdoor ones were exactly the same, except you must never get them mixed up!

From "A Place to Belong" by Cynthia Kadohata

Related Words

• private