company (n.)

mid-12c., "large group of people," from Old French compagnie "society, friendship, intimacy; body of soldiers" (12c.), from Late Latin companio, literally "bread fellow, messmate," from Latin com "with, together" (see com-) + panis "bread," from PIE root *pa- "to feed." Abbreviation co. dates from 1670s. 

Meaning "companionship, consort of persons one with another, intimate association" is from late 13c. Meaning "person or persons associated with another in any way" is from c. 1300. In Middle English the word also could mean "sexual union, intercourse" (c. 1300).

From late 14c. as "a number of persons united to perform or carry out anything jointly," which developed a commercial sense of "business association" by 1550s, the word having been used in reference to trade guilds from late 14c. Meaning "subdivision of an infantry regiment" (in 19c. usually 60 to 100 men, commanded by a captain) is from c. 1400. 

Meaning "person or persons with whom one voluntarily associates" is from c. 1600; phrase keep company "consort" is from 1560s (bear company in the same sense is from c. 1300). Expression two's company "two persons are just right" (for conversation, etc.), is attested from 1849; the following line varies: but three is none (or not), 1849; three's trumpery (1864); three's a crowd (1856). 

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Definitions of company
company (n.)
an institution created to conduct business;
he started the company in his garage
company (n.)
small military unit; usually two or three platoons;
company (n.)
the state of being with someone;
he missed their company
company (n.)
organization of performers and associated personnel (especially theatrical);
the traveling company all stayed at the same hotel
Synonyms: troupe
company (n.)
a social or business visitor;
the room was a mess because he hadn't expected company
Synonyms: caller
company (n.)
a social gathering of guests or companions;
the house was filled with company when I arrived
company (n.)
a band of people associated temporarily in some activity;
the company of cooks walked into the kitchen
Synonyms: party
company (n.)
crew of a ship including the officers; the whole force or personnel of a ship;
Synonyms: ship's company
company (n.)
a unit of firefighters including their equipment;
a hook-and-ladder company
company (v.)
be a companion to somebody;
Synonyms: companion / accompany / keep company