A large molecule consisting of many identical or similar monomers linked together by covalent bonds.

"Polymer" is a large molecule consisting of many identical or similar monomers linked together by covalent bonds.

Explanation:

Polymer, any of a class of natural or synthetic substances composed of very large molecules, called macro molecules, that are multiples of simpler chemical units called monomers. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers make up many of the materials in living organisms, including, for example, proteins, cellulose, and nucleic acids. Polymers are used in almost every area of modern living. Grocery bags, soda and water bottles, textile fibers, phones, computers, food packaging, auto parts, and toys all contain polymers. Even more-sophisticated technology uses polymers.