Fit is a versatile word with several related meanings:

When something fits, it's the right size or shape for its purpose. Your shoes fit when they're neither too tight nor too loose. A puzzle piece fits when it slides perfectly into its spot. When you try on clothes at the store, you're checking whether they fit your body comfortably.

The word also describes being in good physical condition. A fit person exercises regularly and can run, climb, or play sports without getting exhausted quickly. Athletes work hard to stay fit. Your gym teacher might test your fitness level by timing how fast you can run a mile.

Fit can also mean suitable or appropriate for a situation. A fancy restaurant isn't a fit place for wearing muddy boots. When a judge in a story declares someone “unfit to rule,” they're saying that person lacks the qualities needed for that responsibility.

As a verb, to fit something means to install or put it in place. A mechanic fits new brakes on a car. A tailor fits a suit to someone's exact measurements.

A fit can also mean a sudden burst of emotion or activity, like a fit of laughter or a fit of anger.