defective (adj.)

In GRAMMAR, a traditional description of WORDS which do not display all the properties of the CLASS to which they belong. The English MODAL VERBS, for example, are defective in that they do not permit the usual range of verb FORMS, such as an INFINITIVE or PARTICIPLE forms (to may, shalling, etc.). Because of its pejorative connotations in general usage, the term needs to be used cautiously. It tends to be avoided in modern LINGUISTIC analysis (which talks more in terms of IRREGULAR forms and exceptions to RULES), but will be encountered in studies of LINGUISTIC HISTORIOGRAPHY. The distinction between ‘defective’ and ‘irregular’ needs to be appreciated: a defective form is a missing form; an irregular form is present, but does not conform to the rule governing the class to which it belongs.

In PHONOLOGY, descriptive of any pattern which fails to show all the properties of the class to which it belongs. For example, a SEGMENT with a ‘defective DISTRIBUTION’ does not appear in all the ENVIRONMENTS possible for other members of its class (e.g. the distribution of English /h/ is defective, compared with other FRICATIVES, because it cannot appear syllable-finally).