allomorph and zero allomorph

   Allomorph

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

Allomorph is variant form of morpheme about the sounds and phonetic symbols but it doesn’t change the meaning. There are three types of allomorph, phonologically, morphologically and lexically conditioned allomorph.

1. Phonologically conditioned allomorph

The choice of allomorph is predictable on the basis of the pronounciation

• Allomorph of the indefinite article : an (before vowels, ex : an elephant) and a (before consonant, ex : a dog) both of them have meaning one,single.
• Allomorphs of the regular past tense morpheme

1. /id/ after d,t : hated
2. /t/ after all other voiceless sounds : picked
3. /d/ after all other voiced sounds : wedged
4. /im/ before bilabial sounds : impossible
5. /il/ before consonant /l/ : illegal
6. /in/ elsewhere : independent

• Some allomorph of the negative prefix in-

2. Morphologically conditioned allomorph

The choice of allomorph is determined by particular morphemes, not just by their pronounciation, ex : the morpheme –sume in changes to –sumpt- in (consume = consumption)

3. Lexically conditioned allomorph

The choice of allomorph is unpredictable, thus memorized on a word by word basis, ex : ox –plural- oxen, sheep-plural- sheep.

There are examples of allomorph.

Example :

1. Three different allomorphs

   Cats /s/
   
   Dogs/z/
   Boxes/iz/

2. One allomoprh

   Disagreement /dis/
   
   Discount /dis/
   Disbelieve /dis/

      3.Loved /d/

Two differen  allomorphs

     Voiced /d/

     Walked /t/

     Stopped /t/

     Kicked /t/

Note : allomorph occur at every morpheme, ex : agree (one morpheme, one allomorph)

So, allomorph is variant form of a morpheme about the sounds and phonetic symbol but it doesn’t change the meaning. Allomorph has different in pronounciation and spelling according to their condition. It means that allomorph will have different sound, pronounciation or spelling in different condition.

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 with 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, such as the verb "break"), which therefore take priority over the general cases listed above.

Noun	1.	allomorph - any of several different crystalline forms of the same chemical compound; "calcium carbonate occurs in the allomorphs calcite and aragonite" chemical compound, compound - (chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
	2.	allomorph - a variant phonological representation of a morpheme; "the final sounds of `bets' and `beds' and `horses' and `oxen' are allomorphs of the English plural morpheme" morpheme - minimal meaningful language unit; it cannot be divided into smaller meaningful units

https://en.wikipedia.org/wiki/Allomorph

   

zero 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.

A zero, in linguistics, is a constituent needed in analysis but not realized in speech. Specifically in phonology, it refers to an element that is phonologically null. This implies that there is a lack of an element where a theory would expect one. It is usually written with the symbol "∅", . A common ad hoc solution is to use the Scandinavian capital letter Ø instead.
There are several kind of zeros.

• A zero morph, consisting of no phonetic form, is an allomorph of a morpheme that is otherwise realized in speech. In the phrase two sheep-∅, the plural marker is a zero morph, which is an allomorph of -s as in two cows. In the phrase I like-∅ it, the verb conjugation has a zero affix, as opposed to the third-person singular present -s in he likes it.
• A zero pronoun occurs in some languages. In the English sentence nobody knows ∅ the zero pronoun plays the role of the object of the verb, and in ∅ makes no difference it plays the role of the subject. Likewise, the zero pronoun in the book ∅ I am reading plays the role of the relative pronoun that in the book that I am reading. This is also referred to as PRO. In pronoun-dropping languages, including null subject languages such as most Romance languages, the zero pronoun is a prominent feature.
• A zero subordinate conjunction occurs in English in sentences like I know ∅ he likes me, in which the zero conjunction plays the role of the subordinate conjunction that in I know that he likes me.
• A zero article is an unrealized indefinite or definite article in some languages.
• A zero copula,in which a copula such as the verb to be is implied but absent. For example, in Russian the copula is usually omitted in the present tense, as in "Она красивая" (literally: She beautiful), the same happening with colloquial Brazilian Portuguese, as in "irônicos, aqueles" (literally: ironic, those [guys]), though never with the adjective coming after the subject as usual in Romance languages. In English the copula is sometimes omitted in some nonstandard dialects.

examples

• cat = cat + -Ø = ROOT ("cat") + SINGULAR
• cats = cat + -s = ROOT ("cat") + PLURAL

In addition, there are some cases in English where a null morpheme indicates plurality in nouns that take on irregular plurals.

• sheep = sheep + -Ø = ROOT ("sheep") + SINGULAR
• sheep = sheep + -Ø = ROOT ("sheep") + PLURAL

Also, a null morpheme marks the present tense of verbs in all forms but the third person singular:

• (I) run = run + -Ø = ROOT ("run") + PRESENT: Non-3rd-SINGULAR
• (He) runs = run + -s = ROOT ("run") + PRESENT: 3rd-SINGULAR

 https://en.wikipedia.org/wiki/Zero_%28linguistics%29