と言っても過言ではない (といってもかごんではない) Japanese meaning | KotomoraMeanings
1
expression, i-adjective
it is no exaggeration to say; it is not too much to say
A fixed expression used to emphasize that a statement is fully justified, often followed by a strong claim.
に
残
る
偉
業
と
言
っ
て
も
過
言
で
は
ない
。
It is not too much to say that this discovery is a monumental achievement in the history of science.