also: といってもよい
expression
you could say; you might say; verging on the
Used to soften a statement, express approximation, or indicate that something is almost the case. Often follows a noun, adjective, or clause.
彼は天才と言ってもいい。
You could say he's a genius.
この料理は絶品と言ってもいいくらい美味しい。
This dish is so good you might say it's exquisite.
あの映画は傑作と言ってもいい出来だ。
That movie is of a quality you could call a masterpiece.
と言える is a more direct and assertive way to say 'can be said', while と言ってもいい is softer and more subjective, often implying 'it wouldn't be an exaggeration to say'.
と言っても過言ではない is a stronger, more formal expression meaning 'it is no exaggeration to say', whereas と言ってもいい is milder and more conversational.
Phrase composed of the quotative particle と, the te-form of 言う (to say), the particle も (even), and いい (good). Literally 'even if one says it, it is good', i.e., 'it is acceptable to say'.