Abahattha (Prakrit: abasatta, Bengali: অবহট্ঠ ôbôhôtthô, ultimately from Sanskrit apaśabda; "meaningless sound") is a stage in the evolution of the Eastern group of Indo-Aryan languages. The eastern group consists of languages such as Bengali, Maithili, Assamese and Oriya. Abahatta is also called Apabhramsa Avahatta, Apabhramsha Abahatta or Purvi Apabhramsa. Abahatta is considered to follow the Apabhraṃśa stage, i.e. those Apabhraṃśas derived from Magadhi Prakrit.
Abahatta, which existed from the 6th century to 14th century, was contemporaneous with some Apabhraṃśas as well as the early modern languages such as Old Oriya, Old Bengali, Old Maithili and Old Assamese . Many poets composed both in Abahatta and a modern language such as the Charyapada poets, who wrote dohas or short religious verses in Abahatta; the Maithili poet Vidyapati wrote his autobiography Kirtilata in Abahatta.
The Abahattha stage is characterized byLoss of affixes and suffixes
Loss of grammatical gender
Increased usage of short vowels
Nasalisation at the end or in the middle of words
The substitution of h for s
In the history of the Bengali language, the Abahatta stage was followed by the Old Bengali language by c. 1100.