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(n)An unflattering slang term for a squirrel.
Penn State campus is overrun with fat, fearless tree rats.
by Heptune May 11, 2005
More commonly referred to as a common squirrel.
1) The ugly tree rat immediately grabbed the nut and ran.

2) The tree rats were all around the bird feeder.
by Alan G May 26, 2006
That fucking treerat took my nuts!
by The Frisbee Dude September 26, 2008