A monomer is a molecule that forms the basic unit for polymers. They may be considered the building blocks from which proteins are made. Monomers may bind to other monomers to form a repeating chain molecule via a process called polymerization. Monomers may be either natural or synthetic in origin.

i) a molecule that can be bonded to other identical molecules to form a polymer.

ii) Polyesteris a synthetic polymer made of purified terephthalic acid (PTA) or its dimethyl ester dimethyl terephthalate (DMT) and monoethylene glycol (MEG)

Polyester is a synthetic polymer made of purified terephthalic acid (PTA) or its dimethyl ester dimethyl terephthalate (DMT) and monoethylene glycol (MEG). With 18% market share of all plastic materials produced, it ranges third after polyethylene (33.5%) and polypropylene (19.5%).

Polymers are made up of many many molecules all strung together to form really long chains (and sometimes more complicated structures, too).