A companion is someone who you spend time with or who you are travelling with. Fred had been her constant companion for the last six years of her life I asked my travelling companion what he thought of the situation in Algeria
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
one paid to accompany or assist or live with another a person who is frequently in the company of another; "drinking companions"; "comrades in arms"
one paid to accompany or assist or live with another a person who is frequently in the company of another; "drinking companions"; "comrades in arms" a traveler who accompanies you