black racer vs blacksnake

black racer and blacksnake both are nouns.

Word	Noun	Adjective	Verb	Adverb
black racer	Yes	No	No	No
blacksnake	Yes	No	No	No

As nouns, black racer and blacksnake are synonyms defined as:

black racer and blacksnake: blackish racer of the eastern United States that grows to six feet

Other synonyms of black racer include Coluber constrictor.

black racer (noun)	blacksnake (noun)
blackish racer of the eastern United States that grows to six feet	blackish racer of the eastern United States that grows to six feet
	large harmless shiny black North American snake