running mate

a person frequently seen in the company of another inseparable running mates who first met when they were in elementary school Synonyms cohort, companion, compatriot, compeer, comrade, crony, fellow, hobnobber, mate, associateRelated Words colleague, coworker, equal, peer, workmate; accomplice, affiliate, ally, collaborator, confederate, half, partner; buddy, chum, confidant, familiar, friend, hearty, intimate, pal; countryman; classmate, housemate, messmate, playfellow, playmate, roommate, schoolmate, shipmate, teammate; attendant, escort; hanger-on, leech, parasite