WordNet (r) 3.0 (2006):

drifter
    n 1: a wanderer who has no established residence or visible
         means of support [syn: vagrant, drifter, floater,
         vagabond]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "drifter":
   Ahasuerus, Ancient Mariner, Argonaut, Bowery bum, Flying Dutchman,
   Goliard, Odysseus, Oisin, Ossian, Ulysses, angler, beachcomber,
   beggar, beggarly fellow, bird of passage, blighter, budmash, bum,
   bummer, caitiff, derelict, devil, dibber, dibbler, drift netter,
   drunkard, fisher, fisherman, floater, gad, gadabout, go-about,
   good-for-naught, good-for-nothing, guddler, hobo, human wreck,
   itinerant, jacker, jigger, lowlife, mauvais sujet, mean wretch,
   mover, mucker, no-good, pauvre diable, peregrinator, peregrine,
   peripatetic, pilgarlic, piscator, piscatorialist, piscatorian,
   poor creature, poor devil, rambler, roamer, rolling stone, rover,
   runabout, sad case, sad sack, skid-row bum, stiff, straggler,
   street arab, stroller, strolling player, sundowner, swagman,
   the compleat angler, tramp, trawler, troller, troubadour, truant,
   vag, vagabond, vagrant, vaurien, visitant, wanderer,
   wandering minstrel, wandering scholar, wastrel, whaler,
   worthless fellow, wretch