What part of speech is growl?

"Growl" can be either a verb or a noun, depending on its use in a sentence.

Verb: When "growl" is used to describe the act of making a low, guttural sound, it's a verb.

* Example: The dog growled at the stranger.

Noun: When "growl" refers to the sound itself, it's a noun.

* Example: The growl of the engine was deafening.