indoor
adj.located, used, or happening inside a building. You use this to describe things that are protected from the weather outside.
adj.situated, conducted, or used within the interior of a building. Attributive in function; it must precede the noun it modifies.
“The hotel has a large indoor pool.”
“Because of the heavy rain, the school moved the sports day to an indoor gym.”
“The facility offers various indoor activities, including rock climbing and tennis, allowing athletes to train consistently regardless of the seasonal weather conditions.”
The adjective is attributive, meaning it is placed before a noun (e.g., 'indoor plants') and is not typically used after a linking verb like 'is'.
Indoor is an adjective used before nouns; indoors is the adverb used to describe where an action happens or where something is located.
From (with)in + door, first attested 1711.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.