In linguistic typology, polysynthetic languages, formerly holophrastic languages, are highly synthetic languages, i.e., languages in which words are composed of many morphemes (word parts that have independent meaning but may or may not be able to stand alone). They are very highly inflected languages. Polysynthetic languages typically have long "sentence-words" such as the Yupik word tuntussuqatarniksaitengqiggtuq.
Except for the morpheme tuntu "reindeer", none of the other morphemes can appear in isolation.
Whereas isolating languages have a low morpheme-to-word ratio, polysynthetic languages have a very high ratio. There is no generally agreed upon definition of polysynthesis. Generally polysynthetic languages have polypersonal agreement, although some agglutinative languages that are not polysynthetic, such as Basque, Hungarian and Georgian, also have it. Some authors apply the term polysynthetic to languages with high morpheme-to-word ratios, but others use it for languages