1Retirement that occurs when someone reaches the prescribed retirement age (compulsory retirement on reaching retirement age).
彼は今年定年退職を迎える予定だ。
He is scheduled to retire upon reaching the retirement age this year.
父は定年退職後に趣味の写真教室に通い始めた。
After retiring at the mandatory retirement age, my father started attending a photography class as a hobby.
定年退職で会社を去る人のために送別会を開いた。
We held a farewell party for the person leaving the company due to retirement.