Vitiate

verb
take away the legal force of or render ineffective
“invalidate a contract”
Similar: invalidate, void
verb
corrupt morally or by intemperance or sensuality
“debauch the young people with wine and women”
Similar: corrupt, pervert, subvert, demoralize, demoralise, debauch
verb
make imperfect
“nothing marred her beauty”
Similar: mar, impair, spoil, deflower