adverb
(not) in the least; (not) at all
Always used with a negative predicate; emphasizes complete absence or negation. Literary and somewhat old-fashioned; in modern Japanese 少しも or 全然 are more common.
彼の言葉は毫も信じられない。
I cannot believe his words in the least.
その知らせに毫も驚かなかった。
I was not at all surprised by the news.