purr

from WordNet (r) 3.0 (2006)

purr
    n 1: a low vibrating sound typical of a contented cat
    v 1: make a soft swishing sound; "the motor whirred"; "the car
         engine purred" [syn: {whizz}, {whiz}, {whirr}, {whir},
         {birr}, {purr}]
    2: indicate pleasure by purring; characteristic of cats [syn:
       {purr}, {make vibrant sounds}]

from The Collaborative International Dictionary of English v.0.48

Pur \Pur\, v. i. [imp. & p. p. {Purred}; p. pr. & vb. n.
   {Purring}.] [Of imitative origin; cf. Prov. G. purren.]
   To utter a low, murmuring, continued sound, as a cat does
   when pleased. [Written also {purr}.]
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Pur \Pur\, n.
   The low, murmuring sound made by a cat to express contentment
   or pleasure. [Written also {purr}.]
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Purr \Purr\, n.
   The low murmuring sound made by a cat; pur. See {Pur}.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Purr \Purr\, v. i. & t.
   To murmur as a cat. See {Pur}.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

25 Moby Thesaurus words for "purr":
      be in heaven, be pleased, beam, birr, bombilate, bombinate, boom,
      bum, burr, buzz, delight, die with delight, drone, feel happy,
      go into raptures, hum, joy, laugh, sing, smile,
      take great satisfaction, thrum, tread on air, whir, whiz

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