Definition of growls:
(n) :
A deep, rumbling, threatening sound made in the throat by an animal.
(v) :
(intransitive) To utter a deep guttural sound, as an angry animal; to give forth an angry, grumbling sound.
(n) :
(by extension) A similar sound made by a human.
(n) :
(by extension) An aggressive grumbling.
(n) :
(by extension) The rumbling sound made by a human's hungry stomach.
(v) :
(transitive) To express (something) by growling.