What are the opposite words for outdoor?

The antonyms for the word "outdoor" refer to the opposite of outdoor spaces and activities. Some popular antonyms for "outdoor" include "indoor," which refers to certain activities that are done inside; "inside," which refers to being within a structure or object; and "interior," which pertains to the inside of buildings and spaces. Other antonyms for "outdoor" include "enclosed," "internal," and "domestic," all of which suggest the opposite of the great outdoors. While "outdoor" is often used to describe open-air spaces, the antonyms for this word are used to describe spaces that are closed or confined.