Morphology is the branch of linguistics concerned with the internal structure of words and the systematic relationships among their forms. It investigates how meaningful units combine, how new words are created, and how words vary to express grammatical distinctions. In English, for example, cats consists of cat and a plural ending, while teacher contains a verb base and an element forming a noun. Morphology thus examines both the composition of individual words and the patterns connecting words across a language. (openlibrary-repo.ecampusontario.ca)
Words, morphemes, and bases
A central unit of morphological analysis is the morpheme, conventionally defined as the smallest systematic pairing of form with meaning or grammatical function. A free morpheme can occur independently, whereas a bound morpheme must occur with other material. English cat is free, but plural -s is bound. Word boundaries cannot simply be identified with spaces in orthography: writing conventions do not always correspond to the units relevant to grammar, and languages need not have a written form. (openlibrary-repo.ecampusontario.ca)
A root supplies a word’s lexical core. A base is any form to which a morphological operation applies; it may be a root or an already complex expression. Thus, happy is the base for happiness, and happiness can itself serve as the base for plural formation. An affix is a bound element attached to a base. Prefixes precede their bases, suffixes follow them, and infixes occur within them. Roots and bases are therefore not interchangeable concepts: a complex base can contain both a root and several affixes. (pressbooks.openedmb.ca)
Inflection and derivation
Inflection produces grammatical forms of a word rather than a new lexical item. Common inflectional distinctions include number on nouns, tense and aspect on verbs, and comparison on adjectives. English walk, walks, walked, and walking belong to the same verbal paradigm, the organized collection of its inflectional forms. Inflection connects morphology with syntax, because grammatical properties influence how words combine in sentences. (pressbooks.openedmb.ca)
Derivation creates a word with a new meaning, a new lexical category, or both. The suffix -er derives teacher from teach, while -ness derives happiness from happy. Derivation need not change category: re- can attach to a verb to form another verb expressing repetition. Several derivational operations can apply successively, producing families of related words whose members have their own inflectional paradigms. (ecampusontario.pressbooks.pub)
Compounding differs from ordinary affixation by combining multiple roots within a word. It is commonly treated alongside derivation as a major form of word formation. Its analysis requires identifying the constituent roots and determining how their combination affects the resulting word’s category and meaning. (openlibrary-repo.ecampusontario.ca)
Morphological processes and variation
Morphology is not limited to adding segments in sequence. Internal changes can mark grammatical distinctions, as in mouse–mice and write–wrote. Suppletion involves forms that cannot be derived from one another by an ordinary productive operation, exemplified by go–went. Reduplication copies all or part of a base. These processes show why word structure cannot always be represented as a string of easily separable pieces. (openlibrary-repo.ecampusontario.ca)
Nonconcatenative morphology includes patterns expressed through modifications of a base rather than simply through adjoining affixes. Vowel patterns and changes in tone can carry grammatical information. In some languages, a distinction is realized by an entire combination of stem pattern and affixes, making it misleading to assign its meaning to a single detachable segment. (wals.info)
An allomorph is, in a common usage, a variant realization of a morpheme. English past-tense endings, for example, differ in pronunciation according to the preceding sounds. Such variation connects morphology with phonology. Terminology differs among theories: some researchers reserve allomorphy for unpredictable alternatives and distinguish these from forms generated by general phonological rules. (benjamins.com)
Internal structure and meaning
Complex words have hierarchical structure, not merely a fixed linear order of elements. Morphological analysis therefore asks which constituents combine first and which larger constituents they form. This structure can affect meaning: different groupings of the same elements may yield different interpretations. (pressbooks.nvcc.edu)
For example, untieable can mean “able to be untied” or “not able to be tied.” The first interpretation groups un- with tie before adding -able; the second groups tie with -able before adding negative un-. This is structural ambiguity, distinct from ambiguity caused by unrelated words having the same pronunciation. Morphological trees or bracketed representations make these alternative analyses explicit. (pressbooks.nvcc.edu)
Cross-linguistic variation
Linguistic typology compares how languages package grammatical information. Analytic constructions use separate words, whereas synthetic constructions combine grammatical material within a word. English itself exhibits both possibilities: painted expresses past tense through suffixation, while will paint uses a separate auxiliary. Synthesis concerns morphological organization and is not identical to phonological attachment. (wals.info)
Traditional labels such as isolating, agglutinative, and fusional describe broad tendencies, but they combine dimensions that can vary independently. Relevant dimensions include how tightly markers are phonologically connected to a base, how many categories a marker expresses, and how much variation occurs across forms. A cumulative ending may express case and number together, whereas separate endings may express each category individually. Contemporary typological analysis therefore distinguishes these properties rather than assuming that every language fits one uniform morphological type. (wals.info)