Group of contiguous skeletal atoms in a chain, including their side groups, if any, such that the chain itself can be represented as a chain of segments.
Source: PAC, 2015, 87, 71. (Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)) on page 73 [Terms] [Paper]