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