As hungry as a horse is which figure of speech?

"Hungry as a horse" is a simile.

Here's why:

* Simile: A figure of speech that compares two things using the words "like" or "as".

* Metaphor: A figure of speech that directly compares two things without using "like" or "as".

In this case, the phrase directly compares someone's hunger to the hunger of a horse, using the word "as".