invariance (n.)

A principle in some approaches to PHONOLOGY whereby each PHONEME is seen as having a set of defining PHONETIC FEATURES, such that whenever a phoneme occurs the corresponding features will occur. Along with the conditions of LINEARITY and BIUNIQUENESS, the invariance principle establishes a view of phonemic analysis which has been criticized by GENERATIVE phonologists, as part of a general attack on TAXONOMIC phonemics.