to impair the quality of; make faulty; spoil.

to impair or weaken the effectiveness of.

to debase; corrupt; pervert.

to make legally defective or invalid; invalidate

to vitiate a claim.

verb

schedule , set up , aid , assist , help , protect , save

verb

abate , abolish , abrogate , annihilate , annul , delete , deny , invalidate , negate , nullify , quash , recant , revoke , undermine , undo , blemish , blight , brutalize , contaminate , damage , debase , debauch , defile , deprave , deteriorate , devalue , harm , impair , injure , mar , pervert , pollute , prejudice , spoil , sully , taint , tarnish , violate , warp , water down , weaken , detract from , disserve , flaw , hurt , animalize , bastardize , bestialize , canker , demoralize , stain , cancel , set aside , void , adulterate , corrupt , neutralize , poison , sabotage , soil