The Collaborative International Dictionary of English v.0.48:

Hip \Hip\, n. [OE. hepe, AS. he['o]pe; cf. OHG. hiufo a bramble
   bush.] (Bot.)
   The fruit of a rosebush, especially of the English dog-rose
   (Rosa canina); called also rose hip. [Written also hop,
   hep.]
   [1913 Webster]

   Hip tree (Bot.), the dog-rose.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Rosa canina
    n 1: prickly wild rose with delicate pink or white scentless
         flowers; native to Europe [syn: dog rose, Rosa canina]