Routledge Dictionary of Language and Linguistics
Linguistic elements which belong together, but whose linear concatenation is broken by another element, e.g.
a-whole-nother where another is split by the insertion of whole. The description of discontinuous elements presents difficulties for the phrase structure rules, since according to these rules only adjacent constituents can comprise one constituent. In the drawing of discontinuous elements in a tree diagram, there is a crossing of branches which is formally excluded.
References
transformational grammar
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