expression
very ...; nothing more ... than this; as ... as it could possibly be
An emphatic expression attached to adjectives or nouns to express an extreme degree, often with a negative or exclamatory tone. Used in casual speech.
彼の部屋の汚さといったらない。
His room is unbelievably dirty.
試験に落ちた時の悔しさといったらなかった。
I can't tell you how frustrated I was when I failed the exam.