A configurational repeating unit having defined configuration at all sites of stereoisomerism in the main chain (backbone) of a regular macromolecule, a regular oligomer molecule, a regular block or a regular chain.
Source:
PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2291 (https://doi.org/10.1351/pac199668122287)