A retiree is someone who has stopped working at their regular job or career, usually after many years of work and often when they reach an age where they've earned the right to step back from daily employment. When your grandfather retired from being an engineer at age 65, he became a retiree.

People typically become retirees after working for 30, 40, or even 50 years. They might have savings, pensions, or Social Security payments that allow them to live without a regular paycheck. Some retirees travel, volunteer, spend more time with family, or pursue hobbies they never had time for while working. Others start new projects or businesses, just at a more relaxed pace.

In the military, soldiers retire from active duty. In everyday life, you might retire to your room to read. When someone retires from their career, they're stepping back from the working world to enjoy the fruits of their labor.

Not everyone retires at the same age. Teachers, firefighters, and military members often retire earlier than people in other careers. Some people never fully retire and keep working part-time at something they love. A retiree is simply someone who has reached that stage of life where their main working years are behind them.