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).
1835, "system for conveying words over distance by musical notes" (devised in 1828 by French composer Jean-François Sudré (1787-1862); each tone played over several octaves represented a letter of the alphabet), from French téléphone (c. 1830), from télé- "far" (see tele-) + phōnē "sound, voice," from PIE root *bha- (2) "to speak, tell, say." Sudré's system never proved practical. Also used of other apparatus early 19c., including "instrument similar to a foghorn for signaling from ship to ship" (1844). The electrical communication tool was first described in modern form by Philip Reis (1861); developed by Scottish-born inventor Alexander Graham Bell (1847-1922) and so called by him from 1876.
by 1878 [Des Moines Register, May 16], colloquial shortening of telephone (n.), "generally applied to the receiver, but sometimes to the whole apparatus" [Century Dictionary, 1895]. Phone book "publication listing telephone numbers and their associated names" is by 1920; phone booth "small enclosure or stall provided with a public pay-telephone" is by 1906; phone bill "statement of charges for telephone service" is by 1901; phone number (short for telephone number) is by 1906.
1540s, "set of church bells," from ring (v.1). The meaning "a call on the telephone" is from 1900; to give (someone) a ring (up) "call on the telephone" was in use by 1910. Meaning "a ringing sound, the sound of a bell or other sonorous body" is from 1620s; specifically "the ringing sound made by a telephone" by 1951. The meaning "resonance of coin or glass as a test of genuineness" is from 1850, hence transferred use (ring of truth, etc.).