The Collaborative International Dictionary of English v.0.48:

Service \Serv"ice\, n., or Service \Serv"ice\ [Properly, the
   tree which bears serve, OE. serves, pl., service berries, AS.
   syrfe service tree; akin to L. sorbus.] (Bot.)
   A name given to several trees and shrubs of the genus
   Pyrus, as Pyrus domestica and Pyrus torminalis of
   Europe, the various species of mountain ash or rowan tree,
   and the American shad bush (see Shad bush, under Shad).
   They have clusters of small, edible, applelike berries.
   [1913 Webster]

   Service berry (Bot.), the fruit of any kind of service
      tree. In British America the name is especially applied to
      that of the several species or varieties of the shad bush
      (Amelanchier.)
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sorb \Sorb\, n.[L. sorbus the tree, sorbum the fruit; cf. F.
   sorbe. See Service tree.] (Bot.)
   (a) The wild service tree (Pyrus torminalis) of Europe;
       also, the rowan tree.
   (b) The fruit of these trees.
       [1913 Webster]

   Sorb apple, the fruit of the sorb, or wild service tree.

   Sorb tree, the wild service tree.
      [1913 Webster]