noun

a person or animal with whom one spends a lot of time or with whom one travels.

his travelling companion

associate,partner,escort,consort,colleague,workmate,co-worker,compatriot,confederate,ally,friend,intimate,confidant,confidante,comrade,confrère,buddy,pal,chum,crony,cully,spar,sidekick,mate,oppo,china,mucker,marrow,marrer,marra,amigo,compadre,paisan,homeboy,homegirl,gabba,offsider,compeer,consociate

verb

accompany.

he is companioned by a pageboy