Morphology

The word is the nominative unit of language built up by morphemes and indivisible into smaller segments as regards its nominative function.

Morphemic Structure of the Word
The morphological system of language reveals its properties through the morphemic structure of words. So, it is but natural that one of the essential tasks of morphology is to study the morphemic structure of the word.
MORPHEME
Linguists define a morpheme as the smallest unit of language that has its own meaning.

Simple words like giraffe, wiggle, or yellow are morphemes, but so are prefixes like re- and pre- and suffixes like -ize and
-er.
In traditional grammar the study of the morphemic structure of the word is based upon two criteria - positional and semantic (functional).

The semantic criterion involves the study of the contribution of the morpheme to the general meaning of the word.
The base is the semantic core of the word to which the prefixes and suffixes attach.
prefixes and suffixes = affixes
Affixes-
An addition to the base form or stem of a word in order to modify its meaning or create a new word (OXFORD DICTIONARY).
Stem -
The root or main part of a word, to which inflections or formative elements are added (OXFORD DICTIONARY).

Prefixes - An element placed at the beginning of a word to adjust or qualify its meaning (e.g. ex-, non-, re-)
Suffixes - A morpheme added at the end of a word to form a derivative (e.g. -ation, -fy, -ing, -itis).

Further insights into the correlation between the formal and functional aspects of morphemes within the composition of the word may be gained in the light of the so-called "allo-emic" theory put forward by Descriptive Linguistics and broadly used in the cur­rent linguistic research.

In accord with this theory, lingual units are described by means of two types of terms: allo-terms and eme-terms.
Eme-terms denote the generalized invariant units of language characterized by a certain functional status: phonemes, morphemes.
Allo-terms denote the con­crete manifestations, or variants of the generalized units dependent on the regular co-location with other elements of language: allophones, allomorphs.
A set of functional allo-units identified in the text on the basis of their co-occurrence with other lingual units (distribution) is considered as the corresponding eme-unit with its fixed systemic status.

Different morphs representing the same morpheme are called allomorphs, and the phenomenon that different morphs realize one and the same morpheme is known as allomorphy.

The allo-emic identification of lingual elements is achieved by means of the so-called "distributional analysis". The immediate aim of the distributional analysis is to fix and study the units of language in relation to their textual environments, i.e. the adjoining elements in the text.
The environment of a unit may be either "right" or "left", e.g.: un-pardon-able. In this word the left environment of the root is the negative prefix un-, the right environment of the root is the qualitative suffix -able. Respectively, the root -pardon- is the right environment for the prefix, and the left environment for the suffix.

The distribution of a unit may be defined as the total of all its environments; in other words, the distribution of a unit is its envi­ronment in generalized terms of classes or categories.
In the distributional analysis at the morphemic level, phonemic distribution of morphemes and morphemic distribution of morphemes are discriminated. The study is conducted in two stages.
At the first stage, the analyzed text (i.e. the collected lingual materials, or "corpus") is divided into recurrent segments consisting of phonemes. These segments are called "morphs", i.e. morphemic units distributionally uncharacterized, e.g.: the/boat/s/were/gain/ing/ speed.

At the second stage, the environmental features of the morphs are established and the corresponding identifications are affected.
Three main types of distribution are discriminated in the distributional analysis, namely, contrastive distribution, non-contrastive dis­tribution, and complementary distribution.
Contrastive and non-contrastive distributions concern identical environments of different morphs. The morphs are said to be in contrastive distribution if their meanings (functions) are different. Such morphs constitute different morphemes. Cf. the suffixes -(e)d and -ing in the verb-forms returned, returning. The morphs are said to be in non-contrastive distribution (or free alternation) if their meaning (function) is the same. Such morphs constitute "free variants" of the same morpheme. Cf. the suffixes -(e)d and - t in the verb-forms learned, learnt.

As different from the above, complementary distribution concerns different environments of formally different morphs which are united by the same meaning (function). If two or more morphs have the same meaning and the difference in their form is explained by dif­ferent environments, these morphs are said to be in complementary distribution and considered the allomorphs of the same morpheme. Cf. the allomorphs of the plural morpheme /-s/, /-z/, /-iz/ which stand in phonemic complementary distribution; the plural allomorph -en in oxen, children, which stands in morphemic complementary distribution with the other allomorphs of the plural morpheme.
For analytical purposes the notion of complementary distribution is the most important, because it helps establish the identity of outwardly altogether different elements of language, in particular, its grammatical elements.

As a result of the application of distributional analysis to the morphemic level, different types of morphemes have been dis­criminated which can be called "the distributional morpheme types". It must be stressed that the distributional classification of morphemes cannot abolish or in any way depreciate the traditional morpheme types. Rather, it supplements the traditional classification, showing some essential features of morphemes on the principles of environ­mental study.

On the basis of the degree of self-dependence, "free" mor­phemes and "bound" morphemes are distinguished. Bound mor­phemes cannot form words by themselves, they are identified only as component segmental parts of words. As different from this, free morphemes can build up words by themselves, i.e. can be used "freely".
For instance, in the word handful the root hand is a free morpheme, while the suffix -ful is a bound morpheme.

Divide the following words into morphemes:
• pathology
• psychopath
• dermatitis
• endoderm

Chances are that you recognize that there are two morphemes in each word. However, neither part is a free morpheme. Do we want to call these morphemes prefixes and suffixes? Why can’t we call them prefixes and suffixes?

These morphemes seem in an intuitive way to have far more substantial meanings than the average affix does. For example,
un- (unhappy, unwise) simply means ‘not’ and a suffix -ish (reddish, warmish) means ‘sort of ’, psych(o) means ‘having to do with the mind’, -ology means ‘the study of ’, path means ‘sickness’, derm means ‘skin’ and -itis means ‘disease’.
Semantically, bound bases can form the core of a word, just as free morphemes can.

On the basis of formal presentation, "overt" morphemes and "covert" morphemes are distinguished. Overt morphemes are gen­uine, explicit morphemes building up words; the covert morpheme is identified as a contrastive absence of morpheme expressing a certain function. The notion of covert morpheme coincides with the notion of zero morpheme in the oppositional description of grammatical cat­egories.

For instance, the word-form clocks consists of two overt mor­phemes: one lexical (root) and one grammatical expressing the plural. The outwardly one-morpheme word-form clock, since it expresses the singular, is also considered as consisting of two morphemes, i.e. of the overt root and the covert (implicit) grammatical suffix of the singular. The usual symbol for the covert morpheme employed by linguists is the sign of the empty set: Ø.

On the basis of grammatical alternation, "additive" morphemes and "replacive" morphemes are distinguished. Interpreted as additive morphemes are outer grammatical suffixes, since, as a rule, they are opposed to the absence of morphemes in grammatical alternation. Cf. look + ed, small + er, etc. In distinction to these, the root phonemes of grammatical interchange are considered as replacive morphemes, since they replace one another in the paradigmatic forms. Cf. dr-i-ve - dr-o-ve - dr-i-ven; m-a-n - m-e-n; etc.

On the basis of linear characteristic, "continuous" (or "linear") morphemes and "discontinuous" morphemes are distinguished.
By the discontinuous morpheme, opposed to the common, i.e. uninterruptedly expressed, continuous morpheme, a two-element grammatical unit is meant which is identified in the analytical grammatical form comprising an auxiliary word and a grammatical suffix. These two elements, as it were, embed the notional stem; hence, they are symbolically represented as follows:
be ... ing - for the continuous verb forms (e.g. is going);
have ... en - for the perfect verb forms (e.g. has gone);
be ... en-for the passive verb forms (e.g. is taken).