ratter

from WordNet (r) 3.0 (2006)

ratter
    n 1: a disloyal person who betrays or deserts his cause or
         religion or political party or friend etc. [syn:
         {deserter}, {apostate}, {renegade}, {turncoat}, {recreant},
         {ratter}]
    2: any of several breeds of terrier developed to catch rats
       [syn: {rat terrier}, {ratter}]

from The Collaborative International Dictionary of English v.0.48

Ratter \Rat"ter\ (r[a^]t"t[~e]r), n.
   1. One who, or that which, rats, as one who deserts his
      party.
      [1913 Webster]

   2. Anything which catches rats; esp., a dog trained to catch
      rats; a rat terrier. See {Terrier}.
      [1913 Webster]

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