Inflectional Morphology

Glossary of Grammatical and Rhetorical Terms

Inflectional morphology is the study of processes, including affixation and vowel change, that distinguish word forms in certain grammatical categories. Inflectional morphology differs from derivational morphology or word-formation in that inflection deals with changes made to existing words and derivation deals with the creation of new words.

Both inflection and derivation involve attaching affixes to words, but inflection changes a word's form, maintaining the same word, and derivation changes a word's category, creating a new word (Aikhenvald 2007).

Though the inflectional system of Modern English is limited and distinctions between inflection and derivation are not always clear, studying these processes is helpful in understanding the language more deeply. 

Inflectional and Derivational Categories

Inflectional morphology consists of at least five categories, provided in the following excerpt from Language Typology and Syntactic Description: Grammatical Categories and the Lexicon. As the text will explain, derivational morphology cannot be so easily categorized because derivation isn't as predictable as inflection.

"The prototypical inflectional categories include number, tense, person, case, gender, and others, all of which usually produce different forms of the same word rather than different words. Thus leaf and leaves, or write and writes, or run and ran are not given separate headwords in dictionaries.

Derivational categories, in contrast, do form separate words, so that leaflet, writer, and rerun will figure as separate words in dictionaries. In addition, inflectional categories do not, in general, alter the basic meaning expressed by a word; they merely add specifications to a word or emphasize certain aspects of its meaning. Leaves, for instance, has the same basic meaning as leaf, but adds to this the specification of multiple exemplars of leaves.

Derived words, by contrast, generally denote different concepts from their base: leaflet refers to different things from leaf, and the noun writer calls up a somewhat different concept from the verb to write. That said, finding a watertight cross-linguistic definition of 'inflectional' which will let us classify every morphological category as either inflectional or derivational is not easy. ...

[W]e define inflection as those categories of morphology that are regularly responsive to the grammatical environment in which they are expressed. Inflection differs from derivation in that derivation is a lexical matter in which choices are independent of the grammatical environment,"​ (Balthasar and Nichols 2007).

Regular Morphological Inflections

Within the morphological categories of inflection listed above, there are a handful of forms regularly inflected. Teaching Pronunciation: A Reference for Teachers of English to Speakers of Other Languages describes these: "There are eight regular morphological inflections, or grammatically marked forms, that English words can take: plural, possessive, third-person singular present tense, past tense, present participle, past participle, comparative degree, and superlative degree. ...

Modern English has relatively few morphological inflections in comparison with Old English or with other European languages. The inflections and word-class clues that do remain help the listener process incoming language," (Celce-Murcia et al. 1996).

Irregular Morphological Inflections

Of course, there are inflections that do not fit within any of the above eight categories. Linguist and author Yishai Tobin explains that these are left over from past grammar systems. "The so-called irregular inflectional morphology or morphological processes (such as internal vowel change or ablaut (sing, sang, sung)) today represent limited historical remnants of former grammatical inflectional systems which were probably semantically based and are now acquired lexically for frequently used lexical items rather than as grammatical systems,"​ (Tobin 2006).

Dictionaries and Inflectional Morphology

Have you ever noticed that dictionaries don't always include a word's inflections such as the plural form? Andrew Carstairs-McCarthy comments on why that is in his book An Introduction to English Morphology: Words and Their Structure. "[I]t is not correct to say that dictionaries never have anything to say about inflectional morphology. This is because there are two reasons why a word form such as pianists does not have to be listed, and these reasons are interdependent.

The first is that, once we know that an English word is a noun denoting a kind of thing that can be counted (if the noun is pianist or cat, perhaps, but not astonishment or rice), then we can be confident that it will mean simply 'more than one X,' whatever X may be. The second reason is that, unless otherwise specified, we can be confident that the plural form of any countable noun will be formed by adding to the singular form the suffix -s (or rather, the appropriate allomorph of this suffix); in other words, suffixing -s is the regular method of forming plurals.

That qualification 'unless otherwise specified' is crucial, however. Any native speaker of English, after a moment's thought, should be able to think of at least two or three nouns that form their plural in some other way than by adding -s: for example, child has the plural form children, tooth has the plural teeth, and man has the plural men.

The complete list of such nouns in English is not long, but it includes some that are extremely common. What this means for the dictionary entries for child, tooth, man and the others is that, although nothing has to be said about either the fact that these nouns possess a plural form or about what it means, something does have to be said about how the plural is formed," (Carstairs-McCarthy 2002).


  • Aikhenvald, Alexandra Y. "Typological Distinctions in Word-Formation." Language Typology and Syntactic Description. Cambridge University Press, 2007.
  • Bickel, Balthasar, and Johanna Nichols. "Inflectional Morphology." Language Typology and Syntactic Description: Grammatical Categories and the Lexicon. 2nd ed., Cambridge University Press, 2007.
  • Carstairs-McCarthy, Andrew. An Introduction to English Morphology: Words and Their Structure. Edinburgh University Press, 2002.
  • Celce-Murcia, Marianne, et al. Teaching Pronunciation: A Reference for Teachers of English to Speakers of Other Languages. Cambridge University Press, 1996.
  • Tobin, Yishai. "Phonology as Human Behavior: Inflectional Systems in English." Advances in Functional Linguistics: Columbia School Beyond Its Origins. John Benjamins, 2006.
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Nordquist, Richard. "Inflectional Morphology." ThoughtCo, Feb. 5, 2020, Nordquist, Richard. (2020, February 5). Inflectional Morphology. Retrieved from Nordquist, Richard. "Inflectional Morphology." ThoughtCo. (accessed April 2, 2023).