yammer vs utter

yammer is not an adjective while utter is an adjective.

Word	Noun	Adjective	Verb	Adverb
yammer	No	No	Yes	No
utter	No	Yes	Yes	No

As verbs, utter is a hypernym of yammer; that is, utter is a word with a broader meaning than yammer:

Other hypernyms of yammer include emit, let loose, let out.

yammer (adjective)	utter (adjective)
	complete and absolute
	without qualification; used informally as (often pejorative) intensifiers

yammer (verb)	utter (verb)
complain whiningly	express in speech
cry loudly, as of animals	articulate; either verbally or with a cry, shout, or noise
	express audibly; utter sounds (not necessarily words)
	put into circulation