Question

vitiate 【vitiate】v.1.使污浊 2.使无效Pollution from smoke and dust vitiates the air.烟尘的污染使空气污浊。All his attempts to improve were vitiated by his lack of will-power.由于缺乏意志力，他想改良的尝试全部无效。

Accepted Answer

['vɪʃieɪt] 
vitiatemake imperfect
As some sneaky five-year-olds know, crossing one’s fingers while making a promise is an effective way to vitiate, or destroy the validity of, an agreement.
Vitiate is often used when a legal agreement is made invalid, but it can also refer to the debasement or corruption of something or someone. If a malicious five-year-old on the playground teaches the other children to lie with their fingers crossed, she would be responsible for vitiating the playground community. The first syllable of this word is pronounced "vish," like the first syllable in vicious.
All forms of 'vitiate' will appear on average once every 4008 pages.vitiatevitiatedvitiation

Front	vitiate
Pron	['vɪʃieɪt]
Back	【vitiate】 v.1.使污浊 2.使无效 Pollution from smoke and dust vitiates the air. 烟尘的污染使空气污浊。 All his attempts to improve were vitiated by his lack of will-power. 由于缺乏意志力，他想改良的尝试全部无效。
Vocab	vitiatemake imperfect As some sneaky five-year-olds know, crossing one’s fingers while making a promise is an effective way to vitiate, or destroy the validity of, an agreement. Vitiate is often used when a legal agreement is made invalid, but it can also refer to the debasement or corruption of something or someone. If a malicious five-year-old on the playground teaches the other children to lie with their fingers crossed, she would be responsible for vitiating the playground community. The first syllable of this word is pronounced "vish," like the first syllable in vicious. All forms of 'vitiate' will appear on average once every 4008 pages. vitiate vitiated vitiation

Vitiate Fingers Playground Syllable Vɪʃieɪt V.1.使污浊 2.使无效 Pollution