noun
Refers to someone who shows off their knowledge or is overly absorbed in books and learning, often with a negative or mocking tone. The word is relatively rare and literary.
彼は衒学者で、いつも難しい言葉を使いたがる。
He is a pedant who always wants to use difficult words.
あの教授は衒学者だと言われているが
That professor is said to be a pedant, but in fact he has deep knowledge.
知識人 is a broader term for an intellectual, without the negative connotation of pedantry.
Compound of 衒 (gen, 'to show off, display') + 学 (gaku, 'learning') + 者 (sha, 'person'). The exact historical derivation is uncertain, but the word likely entered Japanese from classical Chinese texts.