The Collaborative International Dictionary of English v.0.48:

Glycerin \Glyc"er*in\, Glycerine \Glyc"er*ine\, n. [F.
   glyc['e]rine, fr. Gr. glykero`s, glyky`s, sweet. Cf.
   Glucose, Licorice.] (Chem.)
   An oily, viscous liquid, C3H5(OH)3, colorless and odorless,
   and with a hot, sweetish taste, existing in the natural fats
   and oils as the base, combined with various acids, as oleic,
   margaric, stearic, and palmitic. It may be obtained by
   saponification of fats and oils. It is a triatomic alcohol,
   and hence is also called glycerol. See Note under
   Gelatin.
   [1913 Webster]

   Note: It is obtained from fats by saponification, or, on a
         large scale, by the action of superheated steam. It is
         used as an ointment, as a solvent and vehicle for
         medicines, and as an adulterant in wine, beer, etc.
         [1913 Webster]

WordNet (r) 3.0 (2006):

glycerin
    n 1: a sweet syrupy trihydroxy alcohol obtained by
         saponification of fats and oils [syn: glycerol,
         glycerin, glycerine]