blunder out vs utter

blunder out is not an adjective while utter is an adjective.

Word	Noun	Adjective	Verb	Adverb
blunder out	No	No	Yes	No
utter	No	Yes	Yes	No

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

Other hypernyms of blunder out include mouth, speak, talk, verbalise, verbalize.

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

blunder out (verb)	utter (verb)
utter impulsively	express in speech
	articulate; either verbally or with a cry, shout, or noise
	express audibly; utter sounds (not necessarily words)
	put into circulation