A Dictionary of Linguistics and Phonetics David Crystal

426 segment
segment (n.) A term used in phonetics and linguistics primarily to refer to
any discrete unit that can be identified, either physically or auditorily, in the
stream of speech. Segmentation can take place using either physical or auditory
criteria: in the former case, acoustic or articulatory change-points can be
identified as boundaries of segments; in the latter case, perceptible changes in
quality or quantity, often showing the influence of the language’s phonemic
units, are the basis of division. The term is especially used in phonetics, where
the smallest perceptible discrete unit is referred to as a phone. A feature which
begins or ends within one of the phases of articulation of a segment is called a
subsegmental feature (see onset). ‘Segment’ has developed an abstract sense in
generative phonology, where it is used for a mental unit of phonological
organization – one of a series of minimal units which, however, are not strung
together in a simple linear way. In this model, no physical reality is being
segmented. See also null.
In phonology, a major division is often made into segmental and suprasegmental
(or non-segmental) categories. Segmental phonology analyses the speech
into distinctive units, or phonemes (= ‘segmental phonemes’), which have a
fairly direct correspondence with phonetic segments (alternative approaches involve
analysis in terms of distinctive features and prosodies). Suprasegmental
or non-segmental phonology analyses those features of speech which extend
over more than one segment, such as intonation or (in some theories) vowel
harmony.
The above terminology has been applied analogously to the study of written
texts, where graphs and graphemes are some of the segments identified. The
term is also found in the analysis of higher linguistic units, such as morphemes
or words, as in structuralist analyses of grammar (see immediateconstituent
analysis). In generative syntax, a segment refers to each layer of
the same label created in Chomsky-adjunction structure; the notion is used in
association with category.
segmental tier
see phoneme
segmentator (n.) A device used in instrumental phonetics which plays back a
recording of speech at varying small time intervals, thus allowing a more detailed
study of the segments produced.
segmented discourse representation theory
theory
see discourse representation
selectional feature/restriction/rule A term in generative grammar for a
type of contextual feature, i.e. a syntactic feature which specifies the conditions
relating to where in a deep structure a lexical item can occur.
Selectional features specify the restrictions on the permitted combinations of lexical
items within a given grammatical context. These restrictions are stated with
reference to the relevant inherent features in an adjacent or nearby complex
symbol (within the same structural unit, i.e. they must be clause-mates). For
example, a verb which requires an animate subject noun phrase (cf. *the
stone slept) would have the restriction stated as part of its feature specification,
e.g. as [+[+Animate]]. In government-binding theory, category selection