allo-

A prefix used generally in LINGUISTICS to refer to any noticeable variation in the FORM of a linguistic UNIT which does not affect that unit’s FUNCTIONAL identity in the language. The formal variation noted is not linguistically distinctive, i.e. no change of MEANING is involved. The written language, for example, consists of a series of letters, or GRAPHEMES, but each of these graphemes can be written in several different ways, depending on such matters as linguistic CONTEXT, choice of type, handwriting variation, and so on, e.g. ‘a letter A’ may appear as A, a, a, a, etc. Each of these possibilities is a graphic VARIANT of the abstract grapheme (A): they are all allographs of the grapheme (A). The identity of the word cat stays the same, regardless of whether it is written cat, cAt, cat, etc. (though not all of these would be equally acceptable).

The first relationship of this kind to be established was in PHONOLOGY, viz. the relationship of allophones to PHONEMES. The phonemes of a language are abstractions, and the particular phonetic shape they take depends on many factors, especially their position in relation to other sounds in an utterance. The English phoneme /t/ for example, is usually articulated in ALVEOLAR position (as in eight), but it may occur in DENTAL position, as in eighth, where it has been influenced by the place of articulation of the th sound following. We would thus talk of the alveolar and dental allophones of /t/ in this example. Many allophones are always in principle possible for any phoneme, given the wide range of idiosyncratic pronunciations which exist in a speech community. Textbooks provide information about the major variants, viz. those clearly conditioned by linguistic or social (e.g. ACCENT) contexts. From a terminological point of view, one may also refer to the above phenomenon as an allophonic variant of a phoneme (sometimes simply a ‘phonetic variant’ or a ‘sub-phonemic variant’). The relationship between allophones and phonemes is one of REALIZATION (or EXPONENCE): a phoneme is ‘realized’ by its allophones. The differences between allophones can also be stated using phonological RULES or (as in OPTIMALITY THEORY) through the interaction of CONSTRAINTS. In the latter context, allophony is the term used for cases where a feature does not occur in an inventory, but a context-specific condition overrides the general prohibition.

Later, the notion of variant units in GRAMMAR was established, on analogy with the allophone/phoneme distinction. Many of the MORPHEMES of the language appear in different forms, depending on the context in which they appear. The morpheme which expresses plurality in English, for instance, appears in several variants: cap–caps, log–logs, force–forces, mouse–mice, sheep–sheep, etc. Each of these variant forms – the voiceless [s] of caps, the voiced [z] of logs, the irregular shape of mice, and so on – would be said to be an allomorph of the plural morpheme, and the phenomenon is called allomorphy. They have also been referred to as morpheme (or morphemic) alternants or allomorphic variants.

These are the main allo- terms which have been introduced, all opposed to an -emic term, and the suggestion has been made that this relationship, of allo- to -eme, is an important explanatory principle in linguistic analysis. Certainly many other such allo- relationships have been postulated since the terminology was first introduced in the 1930s. Some are allochrone (non-distinctive variant of a minimal unit of length, or CHRONEME), allokine (non-distinctive variant of a KINEME, i.e. a minimal unit of body movement, such as a gesture or facial expression) and alloseme (non-distinctive variant of a minimal unit of meaning, or SEMEME). None has proved to be as useful as allophone or allomorph, however, and the extent to which this terminology is helpful when applied to such other areas of linguistic analysis – and to behavioral analysis generally, as in the classification of units of dance, song, taste, movement – is disputed.