Glass Transition Temperature: This is the temperature at which an amorphous solid becomes soft upon heating or hard upon cooling.
Polymer: A large molecule composed of repeated subunits, often used to create plastics and resins, many of which are amorphous solids.
Viscosity:A measure of a fluid's resistance to flow. It describes how "thick" a liquid is. For amorphous solids, viscosity increases as temperature decreases.