input signal vs input

input signal and input both are nouns.

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

As nouns, input signal and input are synonyms defined as:

input signal (noun)	input (noun)
signal going into an electronic system	a component of production; something that goes into the production of output
	any stimulating information or event; acts to arouse action
	signal going into an electronic system
	a statement that expresses a personal opinion or belief or adds information

input signal (verb)	input (verb)
	enter (data or a program) into a computer