carbon vs carbon copy

carbon and carbon copy both are nouns.

Word	Noun	Adjective	Verb	Adverb
carbon	Yes	No	No	No
carbon copy	Yes	No	No	No

As nouns, carbon and carbon copy are synonyms defined as:

carbon (noun)	carbon copy (noun)
a copy made with carbon paper	a copy made with carbon paper
an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds
a thin paper coated on one side with a dark waxy substance (often containing carbon); used to transfer characters from the original to an under sheet of paper