In many ways, and quite apart from any phonological markers, the word is a unique entity in grammar, and not just a stage in the progression "from morpheme to utterance". As a grammatical element the word is unique in its relative fixity of internal morphemic structure, its focal status in relation to syntactically relevant categories, and, in inflected words, the stability of its paradigms.
- Robins (2004), Pag. 150