An agglutinative language is a type of synthetic language with morphology that primarily uses agglutination. Words may contain different morphemes to determine their meanings, but all of these morphemes (including stems and affixes) tend to remain unchanged after their unions, although this is not a rule: for example, Finnish is a typical agglutinative language, but morphemes are subject to (sometimes unpredictable) consonant alternations called consonant gradation. Despite the occasional outliers, agglutinative languages tend to have more easily deducible word meanings if compared to fusional languages, which allow unpredictable modifications in either or both the phonetics or spelling of one or more morphemes within a word. This usually results in a shortening of the word, or it provides easier pronunciation.
Agglutinative languages have generally one per affix while fusional languages have multiple. The term was introduced by Wilhelm von Humboldt to classify