More than one; many; much: polyatomic.
More than usual; excessive; abnormal: polydipsia.
Polymer; polymeric: polyethylene.
A prefix meaning "many," as in polygon, a figure having many sides. In chemistry, it is used to form the names of polymers by being attached to the name of the base unit of which the polymer is made, as in polysaccharide, a polymer made of repeating simple sugars (monosaccharides).