leastyoudaoicibaDictYouDict[least 词源字典]
least: [OE] In origin, least is simply the superlative form of less. The prehistoric Germanic ancestor of less was *laisiz (itself a comparative form). Addition of the superlative suffix produced *laisistaz, which passed into Old English as lǣsest. Unchanged, this would have become in modern English *lessest, but it was contracted in the Old English period to lǣst, and so modern English has least.
=> less[least etymology, least origin, 英语词源]
least (adj.)youdaoicibaDictYouDict
Old English læst, earlier læsest "smallest" (superlative of lytel "small"), from Proto-Germanic superlative *laisistaz (see less). Qualifying phrase at least is Middle English æt læstan. As a noun, from early 12c.; as an adverb, c. 1200.