hindlimb vs hind limb

hindlimb and hind limb both are nouns.

Word	Noun	Adjective	Verb	Adverb
hindlimb	Yes	No	No	No
hind limb	Yes	No	No	No

As nouns, hindlimb and hind limb are synonyms defined as:

hindlimb and hind limb: a posterior appendage such as a leg or the homologous structure in other animals

hindlimb (noun)	hind limb (noun)
a posterior appendage such as a leg or the homologous structure in other animals	a posterior appendage such as a leg or the homologous structure in other animals