"Lexeme" may be defined as "a minimal, distinguishable bound or free ordered sequence of phonological segments associated with at least one sense and extrinsic referent, which may be lexically extended by L-derivation [...] and which belongs to an open unparadigmatic class", i.e. the major class items which may fill syntactic nodes: N, V and Adj.
- Beard (2004), a pag.508-509