1. not working or made correctly; having defects: "a faulty brake"Similarmalfunctioningbrokendamageddefectivenot workingnot functioningin disrepairout of orderout of commissioninoperativeunsoundunusableuselessinformal:on the blinkon its last legskaputbustbustedconked outacting/playing upgone haywiregone phutdone forwonkydudknackeredduffon the fritzOppositeworkingfunctioning