expression, godan verb (-tsu)
leave one's seat; stand up from one's seat
Used when someone gets up from a seat, often temporarily, such as during a meeting, meal, or class. Can imply excusing oneself.
会議中に彼は席を立った。
He left his seat during the meeting.
ちょっと席を立ちます。
I'll step away from my seat for a moment.
立ち上がる focuses on the physical action of standing up, while 席を立つ emphasizes leaving the seat, often with the nuance of temporarily departing.
Compound of 席 (seat) + を (object marker) + 立つ (to stand, to leave). The literal meaning is 'to stand from one's seat', extended to leaving a place where one was seated.