Definition: not working properly
Usage: a bad telephone connection; a defective appliance
Similar words: nonfunctional, malfunctioning
Definition: not performing or able to perform its regular function
Usage: a malfunctioning valve
Synonyms: defective
Definition: markedly subnormal in structure or function or intelligence or behavior
Usage: defective speech
Similar words: unnatural, abnormal
Definition: not normal; not typical or usual or regular or conforming to a norm
Usage: abnormal powers of concentration; abnormal amounts of rain; abnormal circumstances; an abnormal interest in food
Definition: having a defect
Usage: I returned the appliance because it was defective
Similar words: imperfect
Definition: not perfect; defective or inadequate
Usage: had only an imperfect understanding of his responsibilities; imperfect mortals; drainage here is imperfect