A phrase meaning 'what is commonly called' or 'so-called'; used to introduce a popular or colloquial name for something.
俗に言う『都市伝説』は、根拠のない噂話が多い。
So-called 'urban legends' are often baseless rumors.
彼は俗に言う天才肌の人間だ。
He is what you'd call a born genius.
俗に言う『草食系男子』という言葉が流行した。
The so-called term 'herbivore men' became popular.