stable companion vs stablemate

stable companion and stablemate both are nouns.

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

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

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

stable companion (noun)	stablemate (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