verb (v)

• corrupt morally or by intemperance or sensuality(verb.social)

  Synonym:
  corrupt, debase, debauch, demoralise, demoralize, deprave, misdirect, pervert, profane, subvert
  

  source: wordnet30
• make imperfect(verb.change)

  Synonym:
  deflower, impair, mar, spoil
  

  source: wordnet30
• take away the legal force of or render ineffective(verb.change)

  Synonym:
  invalidate, void
  Antonym:
  validate
  

  source: wordnet30
• To make vicious, faulty, or imperfect; to render defective; to injure the substance or qualities of; to impair; to contaminate; to spoil; as, exaggeration vitiates a style of writing; sewer gas vitiates the air.(verb)

  source: webster1913