Meaning

noun something that is of no importance

adjective the superlative of `little' that can be used with mass nouns and is usually preceded by `the'; a quantifier meaning smallest in amount or extent or degree

adverb used to form the superlative

originThe adjective, determiner, and noun are derived from Middle English leste, lest, last (“(adjective) smallest, least; (noun) smallest thing, etc.; person or thing least in importance; etc.”), from Old English lǣst, a contraction of læsast, læsest (“least”) (also lærest in only one source), from Proto-Germanic *laisistaz (“smallest, least”), from *laisiz (“less”) (possibly from Proto-Indo-European…

Etymology from Wiktionary, CC BY-SA 3.0