(not) even a little bit; not in the slightest
Used with a negative predicate to emphasize that something is completely absent or not at all the case. Literally 'not even a dewdrop's worth'.
There wasn't even a shred of truth in his words.
I didn't doubt it in the slightest.
Alternate kanji spelling using 程 for ほど; less common but seen in some texts.
Compound of 露 (つゆ, 'dew') + ほど ('extent, degree'), literally 'even the amount of a dewdrop'. Used idiomatically with negatives to mean 'not even a little'.