In morpheme-based morphology
, a morpheme
is the smallest linguistic unit that has semantic meaning
In spoken language, morphemes are composed of phonemes
(the smallest linguistically distinctive units of sound), and in written language morphemes are composed of graphemes
(the smallest units of written language).
The concept morpheme differs from the concept word, as many morphemes cannot stand as words on their own. A morpheme is free if it can stand alone, or bound if it is used exclusively alongside a free morpheme. Its actual phonetic representation is the morph, with the morphs representing the same morpheme being grouped as its allomorphs. English example:
The word "unbreakable" has three morphemes: "un-", a bound morpheme; "break", a free morpheme; and "-able", a bound morpheme. "un-" is also a prefix, "-able" is a suffix. Both "un-" and "-able" are affixes.
The morpheme plural-s has the morph "-s", s, in cats ([kæts]), but "-es", [
ɪz], in dishes ([dɪʃ ɪz]), and even the voiced "-s", [z], in dogs ([dɒgz]). "-s" might even turn into "-ren" ([rɪn]) in children.
Types of morphemes
- Free morphemes like town, and dog can appear with other lexemes (as in town hall or dog house) or they can stand alone, i.e. "free".
- Bound morphemes (or affixes) like "un-" appear only together with other morphemes to form a lexeme. Bound morphemes in general tend to be prefixes and suffixes. Unproductive, non-affix morphemes that exist only in bound form are known as "cranberry" morphemes, from the "cran" in that very word.
- Derivational morphemes can be added to a word to create (derive) another word: the addition of "-ness" to "happy," for example, to give "happiness." They carry semantic information.
- Inflectional morphemes modify a word's tense, number, aspect, and so on (as in the "dog" morpheme if written with the plural marker morpheme "-s" becomes "dogs"). They carry grammatical information.
- Allomorphs are variants of a morpheme, e.g. the plural marker in English is sometimes realized as [-z], [-s] or [-
In natural language processing
and other languages, morphological analysis is a process of segmenting given sentence into a row of morphemes. It 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. Famous Japanese morphological analysers include Juman