Leaving one's seat; standing up and leaving a meeting, ceremony, class, etc., either temporarily or permanently.
急用ができたため、会議を途中で退席した。
Because an urgent matter came up, I left the meeting partway through.
授業中に体調が悪くなり、先生に断って退席した。
I felt unwell during class and excused myself to leave my seat.
式典では途中での退席はマナー違反とされることが多い。
Leaving in the middle of a ceremony is often considered bad manners.