Having defects or imperfections; not working correctly. The faulty wiring caused the lights to flicker intermittently.
Containing mistakes or errors. The faulty reasoning in his argument was quickly pointed out by the professor.
Geology: Marked by or traversed with faults (fractures) in rock strata; faulted. The region's faulty bedrock poses challenges for tunnel engineers.
Archaic: Morally imperfect or blameworthy. Though faulty in many ways, the ruler was loved by his people.