noun. A macromolecule in a living organism that is formed by linking together several smaller molecules, as a protein from amino acids or DNA from nucleotides.

noun. any macromolecule of a living organism that is formed from the polymerization of smaller entities; a polymer that occurs in a living organism or results from life.

"A biopolymer is a naturally-derived alternative to synthetic polymers, which are long molecules that join other molecules together."