output signal vs signal

output signal and signal both are nouns.

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

As nouns, signal is a hypernym of output signal; that is, signal is a word with a broader meaning than output signal:

Other hypernyms of output signal include sign, signaling, signalling.

output signal (noun)	signal (noun)
signal that comes out of an electronic system	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

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

output signal (verb)	signal (verb)
	communicate silently and non-verbally by signals or signs
	be a signal for or a symptom of