Synonyms of in use

Adjective

1. busy, engaged, in use(predicate), occupied (vs. unoccupied)

usage: (of facilities such as telephones or lavatories) unavailable for use by anyone else or indicating unavailability; (`engaged' is a British term for a busy telephone line); "her line is busy"; "receptionists' telephones are always engaged"; "the lavatory is in use"; "kept getting a busy signal"

2. in use, used (vs. misused)

usage: currently being used; "robots are in use throughout industry"