Classification of morphemes

Morpheme

In linguistics, a morpheme is the smallest semantic unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may, or may not stand alone, whereas a word, by definition, is a freestanding unit of meaning. Every word comprises one or more morphemes.

[edit] Free vs. bound

Every morpheme can be classified as either free or bound. These categories are mutually exclusive, and as such, a given morpheme will belong to exactly one of them.

• Free morphemes can function independently as words (e.g. town, dog) and can appear with other lexemes (e.g. town hall, doghouse).
• Bound morphemes appear only as parts of words, always in conjunction with a root and sometimes with other bound morphemes. For example, un- appears only accompanied by other morphemes to form a word. Most bound morphemes in English are affixes, particularly prefixes and suffixes, examples of suffixes are: tion, ation, ible, ing etc.. Bound morphemes that are not affixes are called cranberry morphemes, their nomenclature

Bound morphemes can be further classified as derivational or inflectional.

• Derivational morphemes, when combined with a root, change either the semantic meaning or part of speech of the affected word. For example, in the word happiness, the addition of the bound morpheme -ness to the root happy changes the word from an adjective (happy) to a noun (happiness). In the word unkind, un- functions as a derivational morpheme, for it inverts the meaning of the word formed by the root kind.
• Inflectional morphemes modify a verb's tense or a noun's number without affecting the word's meaning or class. Examples of applying inflectional morphemes to words are adding -s to the root dog to form dogs and adding -ed to wait to form waited.

Allomorph

In linguistics, an allomorph is a variant form of a morpheme. The concept occurs when a unit of meaning can vary in sound without changing meaning. The term allomorph explains the comprehension of phonological variations for specific morphemes.

[edit] Allomorphy in English suffixes

English has several morphemes that vary in sound but not in meaning. Examples include the past tense and the plural morphemes.

For example, in English, a past tense morpheme is -ed. It occurs in several allomorphs depending on its phonological environment, assimilating voicing of the previous segment or inserting a schwa when following an alveolar stop:

• as /əd/ or /ɪd/ in verbs whose stem ends with the alveolar stops /t/ or /d/, such as 'hunted' /hʌntɪd/ or 'banded' /bændɪd/
• as /t/ in verbs whose stem ends with voiceless phonemes other than /t/, such as 'fished' /fɪʃt/
• as /d/ in verbs whose stem ends voiced phonemes other than /d/, such as 'buzzed' /bʌzd/

Notice the "other than" restrictions above. This is a common fact about allomorphy: if the allomorphy conditions are ordered from most restrictive (in this case, after an alveolar stop) to least restrictive, then the first matching case usually "wins". Thus, the above conditions could be re-written as follows:

• as /əd/ or /ɪd/ when the stem ends with the alveolar stops /t/ or /d/
• as /t/ when the stem ends with voiceless phonemes
• as /d/ elsewhere

The fact that the /t/ allomorph does not appear after stem-final /t/, despite the fact that the latter is voiceless, is then explained by the fact that /əd/ appears in that environment, together with the fact that the environments are ordered. Likewise, the fact that the /d/ allomorph does not appear after stem-final /d/ is because the earlier clause for the /əd/ allomorph takes priority; and the fact that the /d/ allomorph does not appear after stem-final voiceless phonemes is because the preceding clause for the /t/ takes priority.

Irregular past tense forms, such as "broke" or "was/ were", can be seen as still more specific cases (since they are confined to certain lexical items, like the verb "break"), which therefore take priority over the general cases listed above.

Null allomorph

In morpheme-based morphology, the term null allomorph or zero allomorph is sometimes used to refer to some kind of null morpheme for which there are also contexts in which the underlying morpheme is manifested in the surface structure. It is therefore also an allomorph. The phenomenon itself is known as null allomorphy, morphological blocking or total morpheme blocking. ^[1]

English

An example of null allomorphy in English is the phrase two fish-Ø which cannot be two fish-es. In addition, according to some linguists such as Radford, in children's language the forms of many auxiliary verbs such as do have null allomorphs in tenseless clauses such as Teddy not go. ^[2]

Stem allomorphy

Allomorphy can also exist in stems or roots, as in Classical Sanskrit:

There are three allomorphs of the stem: /vaːk/, /vaːt͡ʃ/ and /vaːɡ/. The allomorphs are conditioned by the particular case-marking suffixes.

The form of the stem /vaːk/, found in the nominative singular and locative plural, is the etymological form of the morpheme. Pre-Indic palatalization of velars resulted in the variant form /vaːt͡ʃ/, which was initially phonologically conditioned. This conditioning can still be seen in the Locative Singular form, where the /t͡ʃ/ is followed by the high front vowel /i/.

But subsequent merging of /e/ and /o/ into /a/ made the alternation unpredictable on phonetic grounds in the Genitive case (both Singular and Plural), as well as the Nominative Plural and Instrumental Singular. Hence, this allomorphy was no longer directly relatable to phonological processes.

Phonological conditioning also accounts for the /vaːɡ/ form found in the Instrumental Plural, where the /ɡ/ assimilates in voicing to the following /bʱ/.

History

The term was originally used to describe variations in chemical structure. It was first applied to language (in writing) in 1948, by Fatih Şat and Sibel Merve in Language XXIV. ^[1]