The Collaborative International Dictionary of English v.0.48:

Squat \Squat\, n.
   1. The posture of one that sits on his heels or hams, or
      close to the ground.
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   2. A sudden or crushing fall. [Obs.] --Herbert.
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   3. (Mining)
      (a) A small vein of ore.
      (b) A mineral consisting of tin ore and spar. --Halliwell.
          --Woodward.
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   Squat snipe (Zool.), the jacksnipe; -- called also
      squatter. [Local, U.S.]
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The Collaborative International Dictionary of English v.0.48:

Squatter \Squat"ter\ (-t[~e]r), n.
   1. One who squats; specifically, one who settles unlawfully
      upon land without a title. In the United States and
      Australia the term is sometimes applied also to a person
      who settles lawfully upon government land under legal
      permission and restrictions, before acquiring title.
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            In such a tract, squatters and trespassers were
            tolerated to an extent now unknown.   --Macaulay.
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   2. (Zool.) See Squat snipe, under Squat.
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   Squatter sovereignty, the right claimed by the squatters,
      or actual residents, of a Territory of the United States
      to make their own laws. [Local, U.S.] --Bartlett.
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WordNet (r) 3.0 (2006):

squatter
    n 1: someone who settles lawfully on government land with the
         intent to acquire title to it [syn: squatter,
         homesteader, nester]
    2: someone who settles on land without right or title