S/N vs signal/noise

S/N and signal/noise both are nouns.

Word	Noun	Adjective	Verb	Adverb
S/N	Yes	No	No	No
signal/noise	Yes	No	No	No

As nouns, S/N and signal/noise are synonyms defined as:

Other synonyms of S/N include signal/noise ratio, signal-to-noise, signal-to-noise ratio.

S/N (noun)	signal/noise (noun)
the ratio of signal intensity to noise intensity	the ratio of signal intensity to noise intensity