gym rat

[ jim rat ]

noun

, Slang.

1. an exercise and fitness enthusiast who spends a lot of time at the gym, working out frequently or for long periods of time:

   Whether you're a gym rat or a total newbie, these sets are worth exploring.

Word History and Origins

Origin of gym rat¹

First recorded in 1970–75

Example Sentences

These days, beyond simply maintaining his sobriety, the actor has turned into something of a gym rat.

From The Daily Beast