Whirlpool
Eddy, Vortex
noun
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it probably uses the kun'yomi reading. You did not learn this meaning, so here's a mnemonic to help you to remember:
There are lots of whirlpools at the uni zoo (うず). Unis really like being spun around in whirlpools, so when you go to the zoo to see them look out for the tank full of them!
海に渦が発生するのはどうして？
Why do whirlpools appear in the ocean?