severance payment; retirement money (usu. lump-sum); redundancy payment
(compulsory) retirement (e.g. on reaching the age of 65); mandatory retirement; reaching retirement age
letter of resignation; request for retirement
notice of resignation; (one's) resignation; resignation notice
retirement at one's own request
amicable resignation (retirement); resigning (retiring) from one's job of one's free will
encouragement to retire early; retirement stimulus
voluntary resignation; retiring for personal reasons
mass retirement (esp. that of the Japanese baby boomers)
accrued benefit; retirement benefits; post-employment benefits
individual retirement account; IRA
leaving at the convenience of the company
retirement at the behest of one's employer