The romance of Semitic

Most researchers of Semitic morphology refer to the principal characteristic of Semitic morphology as non-linear or non-concatenative. Namely, instead of morphemes being placed linearly, one after the other before or after the word stem, as prefixes and suffixes, as in English, the morphemic structure of Semitic words is characterized by at least two morphemes interwoven (or interdigitated) within each other in a discontinuous (or non-concatenative) manner. One morpheme is inserted into the other (call it template, pattern, or scheme) in certain slots of the word stem structure. As two morphemes, the root and the template are incomplete in every respect, morphologically, phonologically, and semantically, until they merge to form a word or a word stem.

— Joseph Shimron, Language Processing and Acquisition in Languages of Semitic, Root-Based, Morphology