In linguistics and related fields, an emic unit is a type of abstract object. Kinds of emic units are generally denoted by terms with the suffix -eme, such as phoneme, grapheme, and morpheme. The term "emic unit" is defined by Nöth (1995) to mean "an invariant form obtained from the reduction of a class of variant forms to a limited number of abstract units". The variant forms are called etic units (from phonetic). This means that a given emic unit is considered to be a single underlying object that may have a number of different observable "surface" representations. The various etic units that represent a given emic unit of a certain kind are denoted by a corresponding term with the prefix allo- (other, different), such as allophone, allograph, and allomorph. The first emic unit to be considered, in the late 19th century, was the phoneme. The word phoneme comes from the φώνημα, , meaning "that which is sounded", from the verb φωνέω (, 'sound'), which comes in turn from the noun φωνή (, 'sound'). Thus it was originally used (in its French form phonème) to refer simply to a speech sound. But it soon came to be used in its modern sense, to denote an abstract concept. It is by analogy with phoneme that other emic units, such as the morpheme and the grapheme, were named using the -eme suffix. The actual terms "emic unit" and "etic unit" were introduced in 1954 by Kenneth Pike. The prefix allo- used in terms such as allophone is from the ἄλλος (, 'other'). This prefix is also used in chemistry. The following are the most commonly analyzed kinds of emic units in linguistics: A phoneme is an underlying object whose surface representations are phones (speech sounds); different phones representing the same phoneme are called allophones of that phoneme. The choice of allophone may be dependent on the phonological context (neighboring sounds), or may be subject to free variation. A morpheme is an underlying object whose surface representations are meaningful fragments of language; different fragments representing the same morpheme are called allomorphs of that morpheme.
Hervé Bourlard, Hynek Hermansky, John David Scott Dines