n. & v.
n. 1 a (often foll. by in, of) a person who accompanies, associates with, or shares with, another (a companion in adversity; they were close companions). b a person, esp. an unmarried or widowed woman, employed to live with and assist another. 2 a handbook or reference book on a particular subject (A Companion to North Wales). 3 a thing that matches another (the companion of this book-end is over there). 4 (Companion) a member of the lowest grade of some orders of knighthood (Companion of the Bath). 5 Astron. a star etc. that accompanies another. 6 equipment or a piece of equipment that combines several uses.
v. 1 tr. accompany. 2 intr. literary (often foll. by with) be a companion. companion in arms a fellow-soldier. Companion of Honour (in the UK) a member of an order founded in 1917. Companion of Literature (in the UK) a member of an order founded in 1961. companion-set a set of fireside implements on a stand.
[ ME f. OF compaignon ult. f. L panis bread ]