[1] : The Collaborative International Dictionary of English v.0.48

pie \pie\, n. oe. pie, pye; cf. ir.  gael. pighe pie, also
   gael. pige an earthen jar or pot. cf. piggin.
   1. an article of food consisting of paste baked with
      something in it or under it; as, chicken pie; venison pie;
      mince pie; apple pie; pumpkin pie.
      1913 webster

   2. see camp, n., 5. prov. eng. --halliwell.
      1913 webster

   pie crust, the paste of a pie.
      1913 webster
see also:
piggin camp pie crust 

[2] : WordNet (r) 2.0

pie crust
     n : pastry used to hold pie fillings syn: pie shell
see also:
pie shell 

Crust >> C Words
Crust, definition of term: Crust
crust_pag1.html

Apple Pie >> A Words
Apple Pie, definition of term: Apple Pie
apple+pie_pag1.html