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
