branch point

in polymers
https://doi.org/10.1351/goldbook.B00728
Point on a polymer chain at which a branch is attached.
Source:
PAC, 2007, 79, 1801. (Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)) on page 1818 [Terms] [Paper]