adjective

not working or made correctly; having defects.

a faulty brake

malfunctioning,broken,damaged,defective,not working,not functioning,in disrepair,out of order,out of commission,inoperative,unsound,unusable,useless,on the blink,on its last legs,kaput,bust,busted,conked out,acting/playing up,gone haywire,gone phut,done for,wonky,dud,knackered,duff,on the fritz