Northern Andamanese is the critically endangered native language of North Andaman Island. It is closely related to Akakede and seems to have consisted of four mutually intelligible dialects: Akachari (Cari), Akakhora (Kora), Akabo (Bo), and Akajeru (Jeru). Jeru is the only one with speakers remaining.
When the North Andamanese people were resettled to Strait Island, a "koiné" developed from the resulting mixture of dialects. It went extinct in the early 2000s. 
For more specific information, see the individual dialects.
Great Andamanese "koiné".
Great Andamanese koiné is based primarily on Jeru, with lexical and grammatical influence from other Northern Andamanese dialects (Aka-Bo, Aka-Kora and Aka-Cari). 
Phonology.
Vowels.
The Great Andamanese "koiné" has a seven-vowel system.
Grammar.
It is a head-marking polysynthetic and agglutinative language with a SOV pattern. It has a very elaborate system for marking inalienability, with seven possessive markers reflecting different body-divisions. These markers appear as proclitics that classify a large number of nouns as dependent categories.
Vocabulary.
"Koiné" vocabulary:
Place names.
Vocabulary: