The Collaborative International Dictionary of English v.0.48:

Settler \Set"tler\, n.
   1. One who settles, becomes fixed, established, etc.
      [1913 Webster]

   2. Especially, one who establishes himself in a new region or
      a colony; a colonist; a planter; as, the first settlers of
      New England.
      [1913 Webster]

   3. That which settles or finishes; hence, a blow, etc., which
      settles or decides a contest. [Colloq.]
      [1913 Webster]

   4. A vessel, as a tub, in which something, as pulverized ore
      suspended in a liquid, is allowed to settle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

settler
    n 1: a person who settles in a new colony or moves into new
         country [syn: settler, colonist]
    2: a negotiator who settles disputes
    3: a clerk in a betting shop who calculates the winnings

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "settler":
   KO, Maecenas, Santa Claus, almoner, almsgiver, angel, arrival,
   arriviste, assignor, awarder, backer, bestower, cheerful giver,
   clincher, colonial, colonist, colonizer, comer,
   conclusive argument, conferrer, consignor, contributor, crusher,
   death stroke, deathblow, donator, donor, emigrant, end-all, ender,
   entrant, fairy godmother, feoffor, final stroke, financer,
   finisher, finishing stroke, floorer, frontiersman, funder,
   gate-crasher, giver, grantor, greenhorn, homesteader, immigrant,
   imparter, in-migrant, incomer, intruder, kayo, kayo punch,
   knockdown argument, knockout, knockout blow, lady bountiful,
   last dab, nester, new arrival, new boy, newcomer, novus homo,
   parvenu, patron, patroness, philanthropist, pioneer, planter,
   precursor, presenter, quietus, recruit, rookie, sockdolager,
   sooner, squatter, stopper, stowaway, subscriber, sugar daddy,
   supporter, tenderfoot, testate, testator, testatrix, upstart,
   visitant, visitor, vouchsafer