Meaning of LEAST in English

LEAST

n. 25B6; determiner I have not the least idea what this means : SLIGHTEST, smallest, minutest, tiniest, littlest.

25A0; at least AT THE MINIMUM, no/not less than, more than.

Concise Oxford thesaurus English vocabulary.      Краткий оксфордский словарь английского языка тезаурус.