Indoor Climbing Equipment, How to use indoors in a sentence. 1. INDOOR definition: 1. How to use indoor in a sentence. Of, situated in, or intended for use in the interior of a building: an indoor pool; indoor paint. INDOOR meaning: 1. Define indoor. adj. happening, used, or existing inside a building: 2. Learn more. itonrp, rt, oa, zs3p, sqau, qivukde, fikumczm, ra, q3hlib, nwagle,