The plural form of the word 'rund', which means a single lap around a track or a circular path.
Running runds can be tiring but also fun and good exercise.
Examples:
She runs five runds every morning.
Let's see who can run the most runds around the playground.
The dog chases its tail in runds.
The cat tries to catch the mouse in runds.
I ran so many runds that I got very tired.
We counted the runds as we ran.