Gayo (alternatively rendered as Gajo) is an endangered Austronesian language spoken by some 275,000 people in the mountainous region of the Indonesian province Aceh on the Northern tip of the island of Sumatra, specifically around the Central Aceh, Bener Meriah and Gayo Lues regencies. It is classified as belonging to the Western Malayo-Polynesian branch of the Austronesian languages, but is not closely related to other languages. Ethnologue lists Bukit, Dëret, Lues, Lut, and Serbejadi-Lukup as dialects.

Gayo is distinct from other languages in Aceh. The art and culture of the Gayo people is also significantly different compared with other ethnic groups in Aceh.

In 1907, G.A.J. Hazeu wrote a first Gayo–Dutch dictionary for the colonial authorities of the Dutch East Indies.^[2]