열중해요 · 열중했어요 · 열중할 거예요 · 열중하세요
to be absorbed in, to be engrossed in, to concentrate on
Example
아이들이 게임에 열중해서 부르는 소리도 못 들었어요.
The kids were so into the game that they didn't even hear us call.
Word parts
열 heat+중 inside
Literally 'heat inside' — so into something you're fired up.
Good to know
Pronounced [열쭝하다] — the ㅈ is tensed after ㄹ.