noun
pedantry; showing off one's knowledge
Refers to the act of flaunting one's learning or being overly concerned with minor academic details. Often used critically.
彼の話は衒学に過ぎて、聞いている人は退屈そうだった。
His talk was nothing but pedantry, and the listeners looked bored.
衒学をひけらかすより、わかりやすく説明するほうが大切
It's more important to explain things clearly than to show off your learning.
From Chinese 衒學 (xuànxué), literally 'to show off learning'. The kanji 衒 means 'to display' or 'to show off', and 学 means 'learning'.