Vitiate comes from Latin vitiatus, past participle of vitiare ('to spoil, corrupt'), from vitium ('fault, defect, vice'). In current use it is a verb meaning "to spoil, impair, or make legally ineffective". That sense is explained by the older material without requiring a speculative semantic step: the inherited or borrowed base supplies the field of meaning, while the English formation fixes its modern role. The history is mainly one of transmission into English, with the older form and sense carried through borrowing or adaptation. The historical chain includes Latin vitiare and Latin vitium. Related English forms include vice, vicious, and vitiable. Derived forms include vitiation, vitiator, and vitiated. For dictionary purposes, the important point is the continuity between the older form, the route into English, and the present lexical sense.