A flexible segment used to link successive mesogenic units in the molecules of MCPLCs (main-chain polymer liquid crystals) or to attach mesogenic units as side-groups onto the polymer backbone of SGPLCs (side-group polymer liquid crystals).
PAC, 2002, 74, 493. 'Definitions of basic terms relating to polymer liquid crystals (IUPAC Recommendations 2001)' on page 504 (