absolutely not; not at all
Rare emphatic negative adverb, always followed by a negative verb form. Related to 根っから (ねっから), which also means 'completely (not)'.
See also: 根っから
I can't believe his excuse at all.
That story is an absolute lie.
Emphatic reduplication of 根っから (ねっから), itself from 根 (ね, 'root') + から ('from'), meaning 'from the root' → 'completely'. The addition of 葉っから (はっから, from 葉 'leaf') creates a rhyming intensifier.