companion
n. countablen. a person or animal that you spend a lot of time with or travel with. It is someone who keeps you company so you do not feel alone.
n. a person or animal with whom one spends a significant amount of time or travels. Often implies a relationship based on mutual assistance or shared experience rather than deep intimacy or professional obligation.
My dog is a wonderful companion on long walks.
She was looking for a travel companion to share the costs and the driving during her trip across the country.
The elderly man found a loyal companion in his neighbor's cat, which visited him every afternoon and sat quietly by his chair while he read the newspaper.
From Middle English companion, from Old French compaignon (“companion”) (modern French compagnon), from Late Latin compāniōn- (nominative singular compāniō, whence French copain), from com- + pānis (literally, with + bread), a word first attested in the Frankish Lex Salica as a calque of a Germanic word, probably Frankish galaibo, gahlaibō (“messmate”, literally “with-bread”), from Proto-Germanic *gahlaibô. Compare also Old High German galeipo (“messmate”) and Gothic 𐌲𐌰𐌷𐌻𐌰𐌹𐌱𐌰 (gahlaiba, “messmate”); and, for the semantics, compare Old Armenian ընկեր (ənker, “friend”, literally “messmate”). More at co-, loaf. Displaced native Old English ġefēra (literally “fellow traveler”). Compare company and mate.