A term used in linguistics and phonetics to refer to a stretch of speech about which no assumptions have been made in terms of linguistic theory (as opposed to the notion of sentence, which receives its definition from a theory of grammar). In principle, it is a physically definable, behavioural unit, capable of definition in everyday terms. One commonly used definition refers to a ‘stretch of speech preceded and followed by silence or a change of speaker’. But it has proved very difficult to construct a satisfactory definition. The definition just given, for instance, applies equally to a one-word response and a sermon, and attempts have been made to produce a more restricted definition, using such features as pause, rhythm, breath patterns, pitch movement, etc. The analogous term in the study of writing is text.