What does "isan" mean?

The ethnic Lao people who have traditionally lived in Isan.

Isan

adj, name, noun

adj, name, noun ·Rare ·Advanced level

Noun

1
The ethnic Lao people who have traditionally lived in Isan. plural, plural-only

Adjective

1
Of, from, or pertaining to Isan, the Isan people or the Isan language. not-comparable

Proper Noun

1
A large region in northeastern Thailand, on the Khorat Plateau.
2
The language of the Isan people (between Lao and Thai, and sometimes considered a dialect of Lao, although it is written in Thai script).

From Thai อีสาน (ii-sǎan) (same in Isan), claimed to be from Sanskrit ईशान (īśāna, “Shiva of the northeast”).