configurational unit

in polymers
https://doi.org/10.1351/goldbook.C01255
A constitutional unit having at least one site of defined stereoisomerism.
Source:
PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2291 (https://doi.org/10.1351/pac199668122287)