means The point at which a person permanently leaves the workforce, typically in later life, to live off savings, pensions, or accumulated income.

from From the French 'retirer'—to draw back or withdraw—built from 're-' (back) and 'tirer' (to pull or draw). It entered English first as a military term, meaning a withdrawal or retreat from a position, before it softened over the centuries into the gentler retreat from labor we know today. So the word still carries its old battlefield logic: you've held the line long enough, and now you're permitted to fall back.