a member of a typological class of languages in which grammatical meanings are predominantly expressed by synthetic forms. Synthetic languages are in contradistinction to analytic languages, in which grammatical meanings are expressed by means of auxiliary words, and to polysynthetic languages, in which several nominal and verbal lexical meanings are combined within an indivisible complex that outwardly resembles a word.

The basis for the division of languages into synthetic, analytic, and polysynthetic languages is, in fact, syntactic; the division therefore intersects but does not coincide with the morphological classification of languages. The classification of languages according to synthetic and analytic features was proposed by A. von Schlegel (only for inflected languages); A. Schleicher expanded the classification to include agglutinative languages.

The morphemes making up a word in a synthetic language may be combined according to the principles of agglutination or fusion, or they may undergo positional alternations, for example, vowel harmony in Turkish. Synthetic forms occur in a significant number of the world’s languages. Since languages are not, in principle, typologically homogeneous, the term “synthetic language” is applied to languages that exhibit a sufficiently high degree of synthesis. Such languages include the Turkic, Finno-Ugric, most Hamito-Semitic, ancient Indo-European, Mongolian, Manchu-Tungus, some African (such as Bantu), Caucasian, Paleo-Asiatic, and American Indian languages.