sigh vs utter

sigh is a noun but utter is not a noun.

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

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

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

sigh (noun)	utter (noun)
an utterance made by exhaling audibly
a sound like a person sighing

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

sigh (verb)	utter (verb)
heave or utter a sigh; breathe deeply and heavily	express in speech
utter with a sigh	articulate; either verbally or with a cry, shout, or noise
	express audibly; utter sounds (not necessarily words)
	put into circulation