The Collaborative International Dictionary of English v.0.48:

Fawn \Fawn\, v. i. [imp. & p. p. Fawned; p. pr. & vb. n.
   Fawning.] [OE. fawnen, fainen, fagnien, to rejoice,
   welcome, flatter, AS. f[ae]gnian to rejoice; akin to Icel.
   fagna to rejoice, welcome. See Fain.]
   To court favor by low cringing, frisking, etc., as a dog; to
   flatter meanly; -- often followed by on or upon.
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         You showed your teeth like apes, and fawned like
         hounds.                                  --Shak.
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         Thou with trembling fear,
         Or like a fawning parasite, obeyest.     --Milton.
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         Courtiers who fawn on a master while they betray him.
                                                  --Macaulay.
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