To say that forms possess 'a common semantic distinctiveness' does not mean that all the occurrences of these forms must have an identical meaning, but rather that they possess some semantic feature in common which remains constant in all their meanings and which sets them apart from all other forms in the language. The phrase 'common semantic distinctiveness' is essentially a negative formulation. It implies merely that the forms which possess that distinctiveness are in semantic contrast with other forms.
- Nida (1948), a pag.421

Principle 1. Forms which possess a common semantic distinctivness and an identical form in all their occurrences constitute a single morpheme.
- Nida (1948), a pag.419