Deprave

Part of speech: noun (n.)

1. To speak ill of; to depreciate; to malign; to revile. [Obs.] And thou knowest, conscience, I came not to chide Nor deprave thy person with a proud heart. Piers Plowman.

2. To make bad or worse; to vitiate; to corrupt. Whose pride depraves each other better part. Spenser.

Synonyms: corrupt; vitiate; contaminate; pollute.