English Reference

Word

companion

Phoneticscom·pan·ion

US/kəmˈpænjən/

UK/kəmpˈæniən/

Definitions

01a friend or partner

B2

n. a person or animal that you spend time with or travel with.

n. a person or animal with whom one spends a significant amount of time or travels. Often implies a relationship based on mutual company rather than just shared tasks.

“The old man and his dog were constant companions on his morning walks.”

“Finding a reliable travelling companion can be difficult, as long journeys often test even the strongest of friendships.”

Antonyms

02a matching object

C1

n. one of a pair of things that are meant to be used together.

n. one of a pair of things intended to be used together or to complement each other.

“This book is a companion to the television series and explains the history of the show.”

“The volume was designed as a companion to his earlier work on Renaissance architecture, providing the necessary technical diagrams to support his theories.”

Formal

03astronomy

C2 · Science

n. a star or planet that travels through space with another one.

n. a celestial object, such as a star or planet, that is gravitationally bound to or associated with another.

“The bright star has a small companion that is hard to see without a telescope.”

“Observations of the primary star's wobble suggested the presence of a low-mass companion orbiting at a significant distance.”

Technical

Synonyms

04nautical

C2

n. the stairs or the cover for the stairs on a ship.

n. the covering or framework over a hatchway on a ship's deck, or the ladder leading below.

“The sailor hurried down the companion to reach the cabin before the storm hit.”

“Water began to seep through the companion as the waves crashed over the quarterdeck, forcing the crew to secure the hatches.”

Technical

Synonyms

hatchwaycompanionway

Real-World Examples

“He told the conference: "We discovered what we think is a black hole merging with a massive companion star, shredding it into a disk that feeds the black hole.”
ScienceDaily · 16 Aug 2026
“The film’s AI companions are invariably sycophantic, too.”
The Guardian · 11 Aug 2026
“One explanation is that a large galaxy absorbed a smaller companion.”
ScienceDaily · 6 Aug 2026
“Astronomers have been looking for a companion star since its existence was first predicted nearly a century ago.”
Ars Technica · 3 Aug 2026

Etymology

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.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

companionNouncompanionshipNoun

Domains

AstronomyNautical

This entry

Level
C1 · Advanced
Frequency
Common
Updated

Scan code

englishreference.com/q/companion

English Reference