omen vs signal

omen and signal both are nouns.

Word	Noun	Adjective	Verb	Adverb
omen	Yes	No	Yes	No
signal	Yes	Yes	Yes	No

As verbs, signal is a hypernym of omen; that is, signal is a word with a broader meaning than omen:

Other hypernyms of omen include bespeak, betoken, indicate, point.

omen (noun)	signal (noun)
a sign of something about to happen	any nonverbal action or gesture that encodes a message
	any incitement to action
	an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes

omen (adjective)	signal (adjective)
	notably out of the ordinary

omen (verb)	signal (verb)
indicate, as with a sign or an omen	communicate silently and non-verbally by signals or signs
	be a signal for or a symptom of