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Synonyms for Vitiate (same or very similar meaning)

WordNet sense 1 (corrupt morally or by intemperance or sensuality):
corrupt, debase, debauch, demoralize, deprave, misdirect, pervert, profane, subvert, demoralise, pervert

WordNet sense 2 (make imperfect):
deflower, impair, mar, spoil

WordNet sense 3 (take away the legal force of or render ineffective):
invalidate, void

From the ODE community, based on WordNetadd/edit