The Collaborative International Dictionary of English v.0.48:

Glyceryl \Glyc"er*yl\, n. [Glycerin + -yl.] (Chem.)
   A compound radical, C3H5, regarded as the essential radical
   of glycerin. It is metameric with allyl. Called also
   propenyl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

glyceryl
    n 1: a trivalent radical derived from glycerol by removing the
         three hydroxyl radicals