prognosticate vs signal

prognosticate is not a noun while signal is a noun.

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

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

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

prognosticate (noun)	signal (noun)
	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

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

prognosticate (verb)	signal (verb)
make a prediction about; tell in advance	communicate silently and non-verbally by signals or signs
indicate, as with a sign or an omen	be a signal for or a symptom of