What does “야자” mean in Korean?

야자 (yaja) is the word many Korean high schoolers groan about: an evening self-study session that can run late into the night. It’s a clipped compound of 야간자율학습 — 야(간) “night” plus 자(율) “self-directed” study. The irony is baked in: it’s called “self-directed,” yet a teacher often patrols the room and, at some schools, attendance is mandatory or strongly expected rather than truly optional.

The full term 야간자율학습 (yagan-jayul-hakseup) stacks three Sino-Korean chunks: 야간 (night) + 자율 (autonomy) + 학습 (study). Koreans compress it to just the two lead syllables, 야자 — the same shortcut logic behind 야식 (late-night snack) and other 야-words. In this clip the narrator captures the mood perfectly: bored stiff at his desk, he says he’s never been to prison (감옥), but figures 야자 must be what it feels like. You’ll also hear the verb form 야자하다 / 야자를 하다 (“to do yaja”), as in 오늘도 야자를 하고 있다 — “doing yaja again today.”