expression
(not even) a little; (not even) a tiny bit
Used in negative constructions (often with 〜も…ない) to emphasize the complete absence of even a tiny amount. Literally 'even as much as dust'.
彼の話は塵ほども信じられない。
I can't believe even a tiny bit of his story.
この料理には塵ほどの塩も入っていない。
There isn't even a grain of salt in this dish.