Definition: A compound with a particularly large relative molecular mass and repeating structural units formed by thousands of atoms bonded by covalent bonds. (It can be divided into inorganic high molecular weight compounds and organic high molecular weight compounds)

It is a compound formed by the aggregation of a class of molecules with a very high relative molecular mass, also known as polymers, macromolecules, etc. Generally, molecules with a relative molecular mass higher than 10,000 are called polymers. Polymers are usually composed of 103 to 105 atoms connected by covalent bonds. Since polymers are mostly made from small molecules through polymerization reactions, they are often called polymers or high polymers, and the small molecules used for polymerization are called "monomers".

Examples: Natural high molecular weight compounds such as cellulose, protein, silk, rubber, starch, and synthetic materials based on polymers, such as various plastics, synthetic rubber, synthetic fibers, coatings and adhesives, etc.

Organic polymer compounds can be divided into natural organic polymer compounds (such as starch, cellulose, protein, natural rubber, etc.) and synthetic organic polymer compounds (such as polyethylene, polyvinyl chloride, etc.). Their relative molecular mass can range from tens of thousands to millions or even larger, but their chemical composition and structure are relatively simple, often composed of countless (n) small structural units arranged in a repetitive manner.