Vitiate

Part of speech: verb (v.)

1. 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. A will vitiated and growth out of love with the truth disposes the understanding to error and delusion. South. Without care it may be used to vitiate our minds. Burke. This undistinguishing complaisance will vitiate the taste of readers. Garth.

2. To cause to fail of effect, either wholly or in part; to make void; to destroy, as the validity or binding force of an instrument or transaction; to annul; as, any undue influence exerted on a jury vitiates their verdict; fraud vitiates a contract.