In linguistics, a morpheme is the smallest semantically meaningful unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may or may not stand alone, whereas a word, by definition, is a freestanding unit of meaning. Every word comprises one or more morphemes.

Classification of morphemes[link]

Free vs. bound[link]

Every morpheme can be classified as either free or bound. These categories are mutually exclusive, and as such, a given morpheme will belong to exactly one of them.

• Free morphemes can function independently as words (e.g. town, dog) and can appear with other lexemes (e.g. town hall, doghouse).
• Bound morphemes appear only as parts of words, always in conjunction with a root and sometimes with other bound morphemes. For example, un- appears only accompanied by other morphemes to form a word. Most bound morphemes in English are affixes, particularly prefixes and suffixes. Bound morphemes that are not affixes are called cranberry morphemes, their nomenclature derived from the bound, non-affix function of cran- in the word cranberry.

Derivational vs. inflectional[link]

Bound morphemes can be further classified as derivational or inflectional.

• Derivational morphemes, when combined with a root, change either the semantic meaning or part of speech of the affected word. For example, in the word happiness, the addition of the bound morpheme -ness to the root happy changes the word from an adjective (happy) to a noun (happiness). In the word unkind, un- functions as a derivational morpheme, for it inverts the meaning of the word formed by the root kind.
• Inflectional morphemes modify a verb's tense or a noun's number without affecting the word's meaning or class. Examples of applying inflectional morphemes to words are adding -s to the root dog to form dogs and adding -ed to wait to form waited.

Allomorphs[link]

Allomorphs are variants of a morpheme that differ in pronunciation but are semantically identical. For example, in English, the plural marker -(e)s of regular nouns can be pronounced /-z/, /-s/, or /-ɨz/, depending on the final sound of the noun's singular form.

Morphological analysis[link]

This unreferenced section requires citations to ensure verifiability.

In natural language processing for Japanese, Chinese and other languages, morphological analysis is the process of segmenting a sentence into a row of morphemes. Morphological analysis is closely related to part-of-speech tagging, but word segmentation is required for these languages because word boundaries are not indicated by blank spaces.^{[citation needed]}

Changing definitions of morpheme[link]

This unreferenced section requires citations to ensure verifiability.

In generative grammar, the definition of a morpheme depends heavily on whether syntactic trees have morphemes as leafs or features as leafs.

• Direct surface to syntax mapping LFG – leafs are words
• Direct syntax to semantics mapping
  • Leafs in syntactic trees spell out morphemes: Distributed morphology – leafs are morphemes
  • Branches in syntactic trees spell out morphemes:Radical Minimalism and Nanosyntax -leafs are "nano" morpho-syntactic features

Given the definition of morpheme as "the smallest meaningful unit" Nanosyntax aims to account for idioms where it is often an entire syntactic tree which contributes "the smallest meaningful unit." An example idiom is "Don't let the cat out of the bag" where the idiom is composed of "let the cat out of the bag" and that might be considered a semantic morpheme, which is composed of many syntactic morphemes. Other cases where the "smallest meaningful unit" is larger than a word include some collocations such as "in view of" and "business intelligence" where the words together have a specific meaning.

The definition of morphemes also play a significant role in the interfaces of generative grammar in the following theoretical constructs;

• Event semantics The idea that each productive morpheme must have a compositional semantic meaning (a denotation), and if the meaning is there, there must be a morpheme (null or overt).
• Spell-out The interface where syntactic/semantic structures are "spelled-out" using words or morphemes with phonological content. This can also be thought of as lexical insertion into the syntactics

See also[link]

Linguistics[link]

• Alternation (linguistics)
• Hybrid word
• Morphological parsing
• Theoretical linguistics
• Word stem

Lexicology[link]

• Floating tone
• Greek morphemes
• Morphophonology

References[link]

External links[link]

Look up morpheme in Wiktionary, the free dictionary.

• Glossary of reading terms
• Comprehensive and searchable morpheme reference
• Linguistics 001 — Lecture 7 — Morphology by Prof. Mark Lieberman
• Pronunciation of the word morpheme