in-use

  • (s) (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
    engaged, busy,
  • (s) currently being used
    • robots are in use throughout industry

Synonyms

engaged busy

Words of close approximity