Webster's Revised Unabridged Dictionary · 1913

Companion

Companion (kom*pan"yun) , noun

[French compagnon, Old French compaing, from an assumed Late Latin companio (compare companium fellowship, a mess), from Latin com- + panis bread. See Pantry.]

1.
One who accompanies or is in company with another for a longer or shorter period, either from choice or casually; one who is much in the company of, or is associated with, another or others; an associate; a comrade; a consort; a partner.
The companions of his fall. — Milton
The companion of fools shall smart for it. — Bible (KJV) - Proverb xiii. 20 (Rev. Ver.)
Here are your sons again; and I must lose Two of the sweetest companions in the world. — Shakespeare
A companion is one with whom we share our bread; a messmate. — Trench
2.
A knight of the lowest rank in certain orders; as, a companion of the Bath.
3.
A fellow; -- in contempt. [Obsolete] — Shakespeare
4.
(a) (Nautical) A skylight on an upper deck with frames and sashes of various shapes, to admit light to a cabin or lower deck.
(b)
(Nautical) A wooden hood or penthouse covering the companion way; a companion hatch.
Collocations (4)
Companion hatch (Nautical) , a wooden porch over the entrance or staircase of the cabin.
Companion ladder (Nautical) , the ladder by which officers ascend to, or descend from, the quarter-deck. — Totten
Companion way (Nautical) , a staircase leading to the cabin.
Knights companions , in certain honorary orders, the members of the lowest grades as distinguished from knights commanders, knights grand cross, and the like.

Companion , transitive verb

1.
To be a companion to; to attend on; to accompany. [Rare] — Ruskin
2.
To qualify as a companion; to make equal. [Obsolete]
Companion me with my mistress. — Shakespeare