If someone says that they are ‘starving’, they do not mean that they are in fact dying of hunger, but that they are very hungry. This is a simple example of a figure of speech, where the word is used to heighten or increase the state that they are describing. A metaphor or a simile are two of the most common forms used.

I think that you may be confusing “figure of speech” with the parts of speech: nouns, verbs, etc.

I think we may be able to find a figure of speech using any part of speech. Lets try.

noun–I’m as hungry as a bear. the FOS–hungry bear

adverb–I’m dead on my feet. the FOS–dead speaker

verb–He’s lying like a dog. FOS–lying

adjective–She’s as pretty as a picture. FOS–pretty

preposition–They are flying under the radar. FOS–under

conjunction–She looks like something dead, yet she lives!

FOS–yet

exclamation–Run for your lives; the nerd is coming!

FOS–Run………

pronoun–His dad uses him for a punching bag. FOS–him

Realize that the single words identified as FOS are the foci of the FOS. Then you can understand how any part of speech can be the focus of a figure of speech.

An example of a metaphor might be ” He ran like the wind.”

A simile–“He’s as dumb as a stump.”

The easiest definition is to use words so they mean something other than they actually do. There are several types with examples listed in this link: http://www.usingenglish.com/glossary/figure-of-speech.html