Cambridge Dictionary

Meaning of tread water in English

Phrase

to float vertically in the water by moving the legs and the arms up and down: I stopped swimming for a moment and trod water, looking back to the beach.

They were treading water to stay afloat.

He was treading water beside me.

The first thing my dad taught me was how to tread water.

By the time we reached him he was cold and exhausted from treading water.

idiom

to float with your head above the water’s surface and your feet below you by moving your legs and arms up and down

To tread water is also to be active but without making progress or falling further behind:

Stock prices continued to tread water this week.