yolk

yolk
    n 1: the yellow spherical part of an egg that is surrounded by
         the albumen [syn: {egg yolk}, {yolk}]
    2: nutritive material of an ovum stored for the nutrition of an
       embryo (especially the yellow mass of a bird or reptile egg)
       [syn: {yolk}, {vitellus}]
    

Yolk \Yolk\ (y[=o]lk or y[=o]k; 277), n. [OE. yolke, yelke,
   [yogh]olke, [yogh]elke, AS. geoloca, geoleca, fr. geolu
   yellow. See {Yellow}.] [Written also {yelk}.]
   [1913 Webster]
   1. The yellow part of an egg; the vitellus.
      [1913 Webster]

   2. (Zool.) An oily secretion which naturally covers the wool
      of sheep.
      [1913 Webster]

   {Yolk cord} (Zool.), a slender cord or duct which connects
      the yolk glands with the egg chambers in certain insects,
      as in the aphids.

   {Yolk gland} (Zool.), a special organ which secretes the yolk
      of the eggs in many turbellarians, and in some other
      invertebrates. See Illust. of {Hermaphrodite} in Appendix.
      

   {Yolk sack} (Anat.), the umbilical vesicle. See under
      {Unbilical}.
      [1913 Webster]