1.  fellow traveller(n = noun.person) fellow traveler - a communist sympathizer (but not a member of the Communist Party);
is a kind of sympathiser, sympathizer, well-wisher

2.  fellow traveller(n = noun.person) companion, fellow traveler - a traveler who accompanies you;
is a kind of traveler, traveller

air traveller, class fellow, commercial traveller, fellow, fellow feeling, fellow traveler, fellow worker, good fellow, little fellow, odd fellow, teaching fellow, traveller