The Collaborative International Dictionary of English v.0.48:

Wanderer \Wan"der*er\, n.
   One who wanders; a rambler; one who roves; hence, one who
   deviates from duty.
   [1913 Webster]

WordNet (r) 3.0 (2006):

wanderer
    n 1: someone who leads a wandering unsettled life [syn:
         wanderer, roamer, rover, bird of passage]
    2: a computer program that prowls the internet looking for
       publicly accessible resources that can be added to a
       database; the database can then be searched with a search
       engine [syn: spider, wanderer]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "wanderer":
   Ahasuerus, Ancient Mariner, Argonaut, Earth, Flying Dutchman,
   Goliard, Jupiter, Mars, Mercury, Neptune, Odysseus, Oisin, Ossian,
   Pluto, Saturn, Uitlander, Ulysses, Uranus, Venus, alien, asteroid,
   barbarian, bird of passage, deracine, displaced person, drifter,
   emigre, exile, floater, foreign devil, foreigner, gad, gadabout,
   go-about, gringo, inferior planet, itinerant, major planet,
   minor planet, mover, outlander, outlaw, outsider, peregrinator,
   peregrine, peripatetic, planet, planetoid, rambler, refugee,
   roamer, rolling stone, rover, runabout, secondary planet,
   solar system, straggler, stranger, stroller, strolling player,
   superior planet, terrestrial planet, the Wandering Jew, tramontane,
   troubadour, ultramontane, visitant, wandering minstrel,
   wandering scholar