The Collaborative International Dictionary of English v.0.48:

Pippin \Pip"pin\, n. [Probably fr. OE. pippin a seed, as being
   raised from the seed. See Pip a seed.] (Bot.)
   (a) An apple from a tree raised from the seed and not
       grafted; a seedling apple.
   (b) A name given to apples of several different kinds, as
       Newtown pippin, summer pippin, fall pippin, golden
       pippin.
       [1913 Webster]

             We will eat a last year's pippin.    --Shak.
       [1913 Webster]

   Normandy pippins, sun-dried apples for winter use.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Pippin
    n 1: any of numerous superior eating apples with yellow or
         greenish yellow skin flushed with red

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "pippin":
   ace, beaut, corker, crackerjack, daisy, dandy, darb, dilly, dream,
   honey, humdinger, killer-diller, knockout, lollapaloosa, lulu,
   peach, pip, sweetheart, the nuts, whiz