To Nod
To Bow One's Head
intransitive verb, godan verb
If you want to show your agreement with someone you need to nod at them so they know.
うなずく
うなづく
The reading for this word is an exception. Here's a mnemonic to help you remember it:
You seem to nod your head a lot when you're at the unagi zoo (うなず). Unagi zoos are really rare and hard to get into. So while you're there, keep nodding to everyone because you're so honored to be there!
母は話を聞きながら、ウンウンと肯きました。
While I listened to my mother talk, I nodded, "Uh huh."