configurational base unit
in polymers
A constitutional repeating unit in a regular macromolecule, a regular oligomer molecule, regular block or a regular chain, the configuration of which is defined at least at one site of stereoisomerism in the main chain.
Source:
PAC, 1996, 68, 2287 (Glossary of basic terms in polymer science (IUPAC Recommendations 1996)) on page 2291