出典:Wiktionary
From Middle English eschewen, from Anglo-Norman eschiver, (三人称 present eschiu), from Frankish *skiuhijan (“to dread, shun, avoid”); thus a doublet of skew.
For the pronunciation with /ʃ/, compare the development of marshal from Middle English marschal (/marsˈt͡ʃaːl/) or Middle English myssheve, variant of myschef (“hardship”). Variants in /sk/ are either from unattested Middle English *eskewen (from Old Northern French eskiver; compare skew) or are spelling pronunciations.
eschew (三人称単数 現在形 eschews, 現在分詞 eschewing, 過去形および過去分詞形 eschewed)