Meaning of LEAST in English

LEAST

■ determiner & pronoun (usu. the ~ ) smallest in amount, extent, or significance.

■ adjective used in names of very small animals and plants: ~ shrew.

■ adverb to the smallest extent or degree.

Phrases

at ~

1》 not less than; at the minimum.

2》 if nothing else.

3》 anyway.

at the ~ (or very ~ )

1》 not less than; at the minimum.

2》 taking the most pessimistic or unfavourable view.

not in the ~ not in the smallest degree; not at all.

not ~ notably; in particular.

to say the ~ using moderate terms; to put it mildly.

Origin

OE lst , lsest , of Gmc origin; related to less .

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.