(networking) Wi-Fi

be useful, serve / be valid, be usable (e.g. a coupon at a cash register)

a hotel (establishment providing accommodation)

room (of a house or hotel), chamber, apartment, flat / (sumo) a stable where rikishi live and train together under a shisho oyakata (stable master)

business hotel

capsule hotel

a love hotel (short-stay hotel for sex)

(Internet slang) dirty room

at-home clothes

an adult son residing with his parents; generally has not yet or can not come into family inheritance / a female servant working in a daimyō, ōoku, or other high-ranking house