(not) at all; absolutely (not); hardly any
Used with a negative predicate to emphasize that something is almost completely absent or not the case. Literally 'one can say it is entirely...', it strengthens the negation.
He can speak hardly any Japanese at all.
この問題については全くと言っていいほど知られていない。
Almost nothing is known about this issue.
A fixed expression combining 全く (completely) with と言っていいほど (to the extent one can say). The phrase literally means 'to the degree that one can say it is completely...' and is used to intensify a following negative statement.