Agglutinative language

An agglutinative language is a language in which the words are formed by gluing morphemes together. This term was introduced by Wilhelm von Humboldt 1836 to classify languages from a morphological point of view. Agglutinative languages are the most common form of polysynthetic language, and are usually highly inflected. The name was derived from the Latin verb agglutinare, which means "to glue together".

The opposite of a polysynthetic language is an analytic, or isolating language. Polysynthetic languages which are not agglutinative are called fusional languages; they combine morphemes by "squeezing" them together, often changing the morphemes drastically in the process.

It is worth noting that in common usage, "agglutinative" is often used as a synonym for polysynthetic, although it technically is not. When used in this way, the word embraces fusional languages and inflected languages in general. It is also worth noting that the distinction between an agglutinative and a fusional language is often not a sharp one. Rather one should think of these as two ends of a continuum, with various languages falling more toward one end or the other.

Examples of agglutinative languages are Hungarian, Esperanto, Finnish, Japanese, Swahili, Turkish, German and Inuktitut.

As you can see, agglutinative languages are not grouped by the family. Rather, convergant evolution had many separate languages develop this property.