monomer molecule

https://doi.org/10.1351/goldbook.M04019
A molecule which can undergo polymerization thereby contributing constitutional units to the essential structure of a macromolecule.
Source:
PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2289 (https://doi.org/10.1351/pac199668122287)