stablemate vs stable companion

stablemate and stable companion both are nouns.

Word	Noun	Adjective	Verb	Adverb
stablemate	Yes	No	No	No
stable companion	Yes	No	No	No

As nouns, stablemate and stable companion are synonyms defined as:

stablemate and stable companion: a horse stabled with another or one of several horses owned by the same person

stablemate (noun)	stable companion (noun)
a horse stabled with another or one of several horses owned by the same person	a horse stabled with another or one of several horses owned by the same person