From The Collaborative International Dictionary of English v.0.48:
Glycol \Gly"col\, n. [Glycerin + -ol. See Glycerin.] (Chem.)
(a) A thick, colorless liquid, C2H4(OH)2, of a sweetish
taste, produced artificially from certain ethylene
compounds. It is a diacid alcohol, intermediate between
ordinary ethyl alcohol and glycerin.