An agglutinative language is a language that uses agglutination extensively: most words are formed by joining morphemes together. This term was introduced by Wilhelm von Humboldt in 1836 to classify languages from a morphological point of view. It is derived from the Latin verb agglutinare, which means "to glue together".
In agglutinative languages, each affix typically represents one unit of meaning (such as "diminutive", "past tense", "plural", etc.), and bound morphemes are expressed by affixes (and not by internal changes of the root of the word, or changes in stress or tone). Additionally, and most importantly, in an agglutinative language affixes do not become fused with others, and do not change form conditioned by others.
Synthetic languages that are not agglutinative are called fusional languages; they sometimes combine affixes by "squeezing" them together, often changing them drastically in the process, and joining several meanings in one affix (for example, in the Spanish word comí "I ate", the suffix -í carries the meanings of indicative mood, active voice, past tense, first person singular subject and perfective aspect).
The distinction between an agglutinative and a fusional language is often not sharp. Rather, one should think of these as two ends of a continuum, with various languages falling more toward one end or the other. For example, Japanese is generally agglutinative, but expresses fusion in otōto (弟 younger brother ), from oto+hito (originally oto+pito). In fact, a synthetic language may present agglutinative features in its open lexicon but not in its case system (e.g. German, Dutch, and Persian).
Agglutinative languages tend to have a high rate of affixes/morphemes per word, and to be very regular, in particular with very few irregular verbs. For example, Japanese has very few irregular verbs – only two are significantly irregular, and there are only about a dozen others, with only minor irregularity; Ganda has only one (or two, depending on how "irregular" is defined); Turkish has only one and in the Quechua languages all the verbs are regular. Korean language has only ten irregular forms of conjugation. Georgian is an exception; not only is it highly agglutinative (there can be simultaneously up to 8 morphemes per word), but there are also a significant number of irregular verbs, varying in degrees of irregularity.
Examples of agglutinative languages include:
- Algonquian languages, namely Cree and Blackfoot
- Altaic languages
- Athabaskan languages, namely Navajo
- some resources believe Armenian and Persian are the only Indo-European languages which are agglutinative.
- Austronesian languages
- Basque language
- Bantu languages (see Ganda)
- Dravidian languages, most prominent of which are Kannada, Malayalam, Tamil, Telugu and Tulu
- Eskimo–Aleut languages, namely Aleut, Inuktitut, and Yupik
- Igboid languages
- Japonic languages
- Kartvelian languages
- Korean language
- some Mesoamerican and native North American languages including Nahuatl, Huastec, and Salish
- Mongolic languages
- Muskogean languages
- Northeast and Northwest Caucasian languages
- Berber languages
- Some believe that Persian language is the only Iranian language which is agglutinative
- Tungusic languages
- Turkic languages
- many Uralic languages, namely Hungarian, Finnish and Sami languages
- Siouan languages, namely Lakota and Yuchi
- many Tibeto-Burman languages
- Quechua languages and Aymara
Many languages spoken by Ancient Near East peoples were agglutinative:
Some well known constructed languages are agglutinative:
Agglutination is a typological feature and does not imply a linguistic relation, but there are some families of agglutinative languages. For example, the Proto-Uralic language, the ancestor of Uralic languages, was agglutinative, and most descended languages inherit this feature. But since agglutination can arise in languages that previously had a non-agglutinative typology and it can be lost in languages that previously were agglutinative, agglutination as a typological trait cannot be used as evidence of genetic relationship to other agglutinative languages.
Many separate languages developed this property. There seems to exist a preferred evolutionary direction from agglutinative synthetic languages to fusional synthetic languages, and then to non-synthetic languages, which in their turn evolve into isolating languages and from there again into agglutinative synthetic languages. However, this is just a trend, and in itself a combination of the trend observable in Grammaticalization theory and that of general linguistic attrition, especially word-final apocope and elision. This phenomenon is known as language drift.
Sometimes, for different reasons, different aspects of a language do not evolve the same way or at the same speed. For example, the Latin nominal morphology was highly fusional, but the verbal morphology was even more so. They thus simplified at different speeds, and in Romance languages the verbal morphology is more complicated and fusional than the nominal one. In French, over the past centuries, the verbal conjugations went from fusional to more analytic while the nominal and pronominal morphologies grew from already isolating/vestigially fusional to partly agglutinative.
- Stocking, George W. (1995). The Ethnographer's Magic and Other Essays in the History of Anthropology. University of Wisconsin Press. p. 84. ISBN 0-299-13414-8.
- Harper, Douglas. "agglutination". Online Etymology Dictionary.
General references 
- Bodmer, Frederick. Ed. by Lancelot Hogben. The Loom of Language. New York, W.W. Norton and Co., 1944, renewed 1972, pages 53, 190ff. ISBN 0-393-30034-X