Is the English plural '-s' inflection?

Yes. It marks the grammatical category of number on a noun without changing its lexeme or word class, which is the hallmark of inflection.

What is cumulative exponence?

Cumulative exponence is when a single inflectional marker realises several morphosyntactic features at once, as when a Latin verb ending simultaneously signals person, number, tense, and mood.

Inflectional Morphology

Inflectional morphology realises the grammatically required forms of a lexeme, marking categories such as tense, number, case, and agreement without creating a new word.

Definition

Inflectional morphology is the system of obligatory grammatical marking on lexemes that realises morphosyntactic features required by their context, yielding the distinct word forms of a single lexeme.

Scope

This topic covers inflection: the morphosyntactic categories it expresses (such as tense, aspect, mood, number, person, gender, and case), the means by which they are realised (affixation, stem change, and others), and the feature systems that organise them. It does not cover word formation, the structure of full paradigms and syncretism, or the inflection-derivation boundary, which are handled in sibling topics.

Core questions

Which grammatical categories are expressed through inflection?
How are morphosyntactic features realised on words?
What is the role of agreement in inflectional systems?
How do inflectional systems differ across languages?

Key concepts

morphosyntactic feature
tense, aspect, and mood
number, person, and gender
case marking
agreement
affixation versus stem alternation

Key theories

Paradigm-function morphology: Stump's realisational theory in which inflected forms are produced by a paradigm function that maps a lexeme and a set of morphosyntactic features onto a fully specified word form via ordered realisation rules.
Feature-based agreement: Corbett's account of agreement as the systematic covariance in form between a controller and a target, organised by features such as person, number, and gender and by canonical and non-canonical patterns.

History

Inflection was a core concern of classical and structuralist grammar, organised around the notion of the paradigm. Generative morphology initially treated inflection through affixation rules, but realisational theories developed by Anderson, Stump (2001), and others shifted the focus to the mapping from feature sets to forms. Corbett's (2006) typological work on agreement and features provided a cross-linguistic framework for the categories inflection encodes.

Debates

Incremental versus realisational inflection: Whether each affix incrementally adds a piece of morphosyntactic content, or whether forms realise complete feature bundles, with the latter better handling extended exponence and cumulation.

Key figures

Gregory Stump
Greville Corbett
Martin Haspelmath
Stephen R. Anderson

Seminal works

stump2001
corbett2006
haspelmathsims2010

Frequently asked questions

Is the English plural '-s' inflection?: Yes. It marks the grammatical category of number on a noun without changing its lexeme or word class, which is the hallmark of inflection.
What is cumulative exponence?: Cumulative exponence is when a single inflectional marker realises several morphosyntactic features at once, as when a Latin verb ending simultaneously signals person, number, tense, and mood.