1. Basic concepts
The most basic concept of morphology is ‘word’. But when a dictionary is made, not every sequence of letter or sounds has its own entry. For instance, the live, lives, lived, living are pronounced and written and are different words. But a dictionary will list only a single entry live. Dictionary users are expected to know that live, lives, lived, and living are different realizations of the ‘same’ word LIVE. Thus, there are two different notions of ‘word’: the dictionary word and text word.
Since this distinction is central to morphology, there are special technical terms for the two notions, lexeme and word-form.
1.1. Lexemes and word forms
A dictionary word is called a lexeme. The term is related to the term lexicon which is the mental dictionary people have in their heads. Lexemes are abstract entities and can be thought of as sets of word-forms.
A text word is called a word-form. Word-forms are concrete in that they can be pronounce and used in texts. Every word-form belongs to one lexeme, e.g. word-form lived belongs to the lexeme LIVE (capital letters are used to designate lexemes). The set of word-forms that belongs to a lexeme is called paradigm. English nouns have two or three word-forms, e.g.
Different lexemes may be related to each other, and the set is sometimes called a word family. E.g.: READ, READABLE, UNREADABLE, READER, READABILITY, and REREAD. These words are given their own dictionary entries. READABLE, UNREADABLE, READER, READABILITY, and REREAD are called complex lexemes and they generally denote new concepts.
There are two kinds of morphological relationships. Inflection (inflectional morphology0 denotes the relationship between word-forms of a lexeme; and derivation (derivational morphology) which denotes the relationship between lexemes of a word family. A derived lexeme is called a derivative. Derivation normally involves change of word class (category, or part of speech).
Some morphological complex words belong to two or more word families simultaneously. For instance, the FIREWOOD belongs both in the family of FIRE and the family of WOOD. Such relationships are called compounding, and the lexeme FIREWOOD is called a compound lexeme. Compounding if often grouped together with derivation under the category of word formation (i.e. lexeme formation)
Morphological structure exists if a group of words shows partial form-meaning resemblances. Parts of word-forms have different meanings. For instance: wash, wash-es, wash-er, wash-able. The words are easily segmented, i.e. broken into individually meaningful parts. The parts are called morphemes. Words may consists of more than one morphemes, e.g. read-abil-ity, un-friend-li-ness. Morphemes can be defined as the smallest meaningful constituents of linguistic expression. A morpheme has meaning. When we have a sentence such as Camillia met an unfriendly chameleon, we can diide it into meaningful parts in various ways: (1) Camillia – met- an unfriendly chameleon (N+V+NP); (2) an -unfriendly – chameleon (indefinite article + Adj + N); (3) un - friend – ly (prefix + stem+ suffix). Stem is the base of an inflected word-form. Morphemes are the ultimate elements of morphological analysis.
Morphemes can have various kinds of meanings. Some meanings are concrete and can be described easily, eg. wash, read, able (from readable); but other meaning are abstract and more difficult to describe, e.g. –ity in readability means ‘ the quality’ so the quality of being readable’.
1.3 Stem, bases, roots, and affixes
Stem is the base of an inflected word-form. The part of the word that an affix is attached to is called the base, e.g in read-er, read-able, un-read-able, re-read, the base is read, and -er, -able are suffixes, re- is a prefix, un - able are confix or circumfix (there is no form *unread; so un- must co-occur with -able in this particular case) a base that cannot be analysed further is called root. So in readability, read is the root and the base for readable, and readable is the base for readability, but it is not a root. In English there is no infix, -um- in s-um-ulat which means ‘write ‘ in Tagalog. Affix is a cover term to denote a short morpheme with an abstract meaning. Affixes are similar to roots in that they are primitive elements. In English the stem is the same as a citation form, that is a word-form that is used by convention to refer a lexeme (a dictionary form). A lexeme is an abstract entity that cannot be segmented.
English has a number of morphemes that are difficult to classify as roots or affixes , eg. Biorhythm, bioethics, technocrat, democrat. The elements bio- and -crat could be regarded as affixes because they do not occur as independent lexemes; they are often referred to as bound roots.