Vanquish

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Middle English: from Old French vencus, venquis (past participle and past tense of veintre ), vainquiss- (lengthened stem of vainquir ), from Latin vincere ‘conquer’.

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From Middle English venquysshen, vaynquisshen, borrowed from a conjugated form of Old French veincre, from Latin vincō.

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vanquish (v.)

mid-14c., "to defeat in battle, conquer," from Old French venquis-, extended stem of veintre "to defeat," from Latin vincere "to overcome, conquer" (from nasalized form of PIE root *weik- (3) "to fight, conquer"). Influenced in Middle English by French vainquiss-, present stem of vainquir "conquer," from Old French vainkir, alteration of veintre. Related: Vanquished; vanquishing.