IPA: /ˌvɪʃiˈeɪʃən/
KK: /ˈvɪʃiˌeɪʃən/
A decrease in the quality or value of something, often due to corruption or impairment.
The vitiation of the contract led to its invalidation in court.
Vitiation → It is formed from "viti-" (from Latin "vitium", meaning fault or defect) and "-ation" (meaning the action or process of). The word "vitiation" refers to the process of making something faulty or defective.
Think of 'fault' ('vitium') and remember that 'vitiation' means the process of making something faulty.