Nonconcatenative morphology, also called discontinuous morphology and introflection, is a form of word formation and inflection in which the root is modified and which does not involve stringing morphemes together sequentially.
Types
Ablaut
In English, for example, while plurals are usually formed by adding the suffix -s, certain words use nonconcatenative processes for their plural forms:
This specific form of nonconcatenative morphology is known as base modification or ablaut, a form in which part of the root undergoes a phonological change without necessarily adding new phonological material. In traditional Indo-Europeanist usage, these changes are termed ablaut only when they result from vowel gradations in Proto-Indo-European. An example is the English stem s⌂ng, resulting in the four distinct words: sing-sang-song-sung. An example from German is the stem spr⌂ch "speak", which results in various distinct forms such as spricht-sprechen-sprach-gesprochen-Spruch. Changes such as foot/feet, on the other hand, which are due to the influence of a since-lost front vowel, are called umlaut. Other forms of base modification include lengthening of a vowel, as in Hindi:
Consonant apophony, such as the initial-consonant mutations in Celtic languages, also exists.
Transfixation
Another form of nonconcatenative morphology is known as transfixation, in which vowel and consonant morphemes are interdigitated. For example, depending on the vowels, the Arabicconsonantal root k-t-b can have different but semantically related meanings. Thus, 'he wrote' and 'book' both come from the root k-t-b. Words from k-t-b are formed by filling in the vowels, e.g. kitāb "book", kutub "books", kātib "writer", kuttāb "writers", kataba "he wrote", yaktubu "he writes", etc. In the analysis provided by McCarthy's account of nonconcatenative morphology, the consonantal root is assigned to one tier, and the vowel pattern to another.
Reduplication
Yet another common type of nonconcatenative morphology is reduplication, a process in which all or part of the root is reduplicated. In Sakha, this process is used to form intensified adjectives: "red" ↔ "flaming red".
Truncation
A final type of nonconcatenative morphology is variously referred to as truncation, deletion, or subtraction; the morpheme is sometimes called a disfix. This process removes phonological material from the root. In French, this process can be found in a small subset of plurals : /os/ "bone" ↔ /o/ "bones" /bœf/ "ox" ↔ /bø/ "oxen"
Nonconcatenative morphology is extremely well developed in the Semitic languages in which it forms the basis of virtually all higher-level word formation. That is especially pronounced in Arabic, which also uses it to form approximately 41% of plurals in what is often called the broken plural.
