Theoretical Grammar of English

The Number and Case in Modern English Nouns

Number is a grammatical category of nouns which denotes the number of objects, expressed by a word.
In English there are two numbers: singular and plural. The formal signal of the singular number is a zero morpheme, while the usual signal of plurality -/e/s. The formation of plural by
means -/e/s is considered to be productive, but in Modern English there are some non-productive types of plural number, as for instance:

1. 
   suffix - en : ox - oxen
   
2. 
   variation of vowels in the root of a word:
   

tooth-teeth; goose-geese; mouse-mice; man-men,

3. 
   variation of vowels of the root + suffix- "ren" children;
   
4. 
   homonymous forms for both sing and plural: sheep – sheep
   

deer – deer swine – swine
This type of formation of plurality was a norm for the whole group of words in Old English, but in Modern English only some words have been preserved.
Non-productive type of number we find in some borrowed words from Latin and Greek, such as: datum – data basis – bases /si:z/
memorandum – memoranda crisis – crises /si:z/ formula – formulae /i: / analysis – analyses /si:z/
These words form their plural as per the norms of Latin and Greek languages, though some of them form their plural according to English: formulas, memorandums.
With regard to the category of number English nouns fall under two subclasses: countable and uncountable. The latter is again subdivided into those having no plural form and those having no singular. The former type is called Pluralia tantum: clothes, goods, the latter - singularia tantum: milk, water.
The lexical and grammatical morphemes of a word linked together so closely that sometimes it seems impossible to separate them. The relation between foot and feet, goose and geese, man and men is similar to the relation between.
bag – bags; desk – desks
The examples above remind us the facts of the Arabic language. In this language lexical morphemes are usually consist of consonants. They are united with vocalic morphemes grammatical in character and occurring between consonants, e.g.,
Ktb
ktaab - a book kutub - books katab - he wrote kaatib - clerk kattab - he dictated.
In these examples consonants Ktb are lexical morphemes as well as English f...t, g...s, m...n and so on. But there are two different things here to be distinguished. Arabic is a Semitic synthetic language while English is an Indo-European analytical one. If a discontinuous lexical morpheme is characteristic to the system of Arabic, for English it is an exception. English forms its plural forms by - /e/ s.
Some linguists consider the case as above as internal inflection inserted into a lexical one / -u- / and / - i : - /
/ as it is in Arabic / and others think of vowel change / u > i: /. To be consistent we'll regard nouns above as follows:
sing. Man - pl /man + s/ = men
The group of pluralia tantum is mostly composed on nouns which express things as objects consisting of two or more parts, e.g. trousers, scissors. Nouns like clothes, sweets must also be referred to pluralia tantum since they denote collective meaning. The - s, here is lexicalized and developed into an inseparable part of the stem. The suffix here is no longer a grammatical morpheme.
In compound nouns both the 1^st and 2^nd components may be pluralized: father-in-law / 1^st /, suitcase / 2^nd /, Manservant—menservants etc.