squatter

from The Century Dictionary.

• To plunge into or through water.
• noun One who or that which squats.
• noun One who settles on new land, particularly on public land, without a title.
• noun Hence One who or that which assumes domiciliary rights without a title.
• noun One who obtains from the government a right of pasturage on moderate terms; also, any stock-owner.
• noun In ornithology, same as krieker.
• To make a noise like a flock of wild fowl flapping their wings against or through the water.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who squats
• noun (Zoöl.) See Squat snipe, under Squat.
• noun [Local, U.S.] the right claimed by the squatters, or actual residents, of a Territory of the United States to make their own laws.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One who squats, sits down idly.
• noun Australia, historical A large-scale grazier and landowner.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who settles on land without right or title
• noun someone who settles lawfully on government land with the intent to acquire title to it