The notion of simplicity in language is difficult to define with precision, and we make no attempt here to offer an adequate definition, but modifications that seem intended in a fairly obvious way to make utterances easier to perceive, understand, or produce may be regarded as simplifying processes if they omit material, reduce irregularity, or make sound-meaning correspondences more transparent. Such modifications occur in phonology, morphosyntax and lexicon.
- Ferguson-DeBose (1977), Pag. 105