Definitions for olestraoʊˈlɛs trə
Random House Webster's College Dictionary
a synthetic oil used as a substitute for dietary fat: not digested or absorbed by the human body.
Origin of olestra:
1990–95; ol- (< L oleum oil) +-estra, alter. of (poly)ester
A fat substitute (a glyceride of sucrose) that cannot be easily digested and therefore adds no fat, calories, or cholesterol to food products; also used as an industrial lubricant.