제대가 · 제대를
discharge from the military
Example
형은 작년에 제대하고 다시 대학교에 다니고 있어요.
My older brother was discharged last year and is back in college.
Word parts
제 remove+대 unit, group
Literally 'removed from the unit'.
Good to know
In official settings 전역 is preferred, but 제대 is very common in everyday speech.