Nouns

(n)leastsomething that is of no importance“it is the least I can do”, “that is the least of my concerns”

Adjectives

(a)leastthe 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“didn't care the least bit”, “he has the least talent of anyone”

Adverbs

(r)least, to the lowest degreeused to form the superlative, smallest in size or degree“The garter snake is the least dangerous snake”