high sign vs signal

high sign and signal both are nouns.

Word	Noun	Adjective	Verb	Adverb
high sign	Yes	No	No	No
signal	Yes	Yes	Yes	No

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

Other hypernyms of high sign include sign, signaling, signalling.

high sign (noun)	signal (noun)
a silent signal of warning or recognition	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

high sign (adjective)	signal (adjective)
	notably out of the ordinary

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