noun
or polyester plastic
: any of various synthetic resins or plastics consisting of or made from polyesters: as
a. : alkyd
b. : a resin that has the same chemical composition as the common polyester fiber but that is extruded as a film (as for use in packaging, as electrical insulation, or as a base for magnetic recording tapes)
c. : a thermosetting resin that is made from an unsaturated polyester (as one formed from a glycol and maleic acid or fumaric acid), cured by copolymerization (as with styrene), and often reinforced with fillers (as glass fibers) and that is used chiefly in impregnating and laminating and in making cast and molded products