Adat (Jawi: عادت) is the generic term derived from Arabic language for describing a variety of local customary practices and tradition as observed by Muslim communitites in North Caucasus, Central Asia and Southeast Asia. Despite its Arabic origin, the term adat resonates deeply throughout the Maritime Southeast Asia, where due to colonial influence, its usage has been systematically institutionalised into various non-Muslim communities. Within the region, the term refers, in a broader sense, to the customary norms, rules, interdictions, and injunctions that guide individual's conduct as a member of the community and the sanctions and forms of address by which these norms and rules, are upheld. Adat also include the set of local and traditional laws and dispute resolution systems by which society was regulated.
The word adat is derived from the Arabic word ʿādā́t (عادات), the plural form of ʿā́da (عادَة), meaning custom, or habit and is considered as synonymous with urf (عرف), something which is commonly known or accepted. It generally refers to the result of long-standing convention, either deliberately adopted or the result of unconscious adaptation to circumstances, that has been followed where practical considerations have been uppermost.
Prior to the arrival of Islam, the peoples of North Caucasus and Central Asia had long-established codes of legal and civil law, which in the Islamic period came to be known by the term adat. Adat in traditional central asian societies are guided by authoritative members of communities, usually councils of Aqsaqals. It is based on a tribal code of conduct and on centuries of experience in conflict resolution between individuals, communities, and tribes. In North Caucasus, the traditional value codex of adat held that the Teip ('clan') was the chief reference for loyalty, honor, shame and collective responsibility. The Russian empire's colonial administration did not interfere with local legal practices and delegated the administration at the local community level to the councils of aqsaqals and teips. So did the Bolsheviks during the first years of the revolution of 1917. The adat was practiced among the central asians and north caucasians up until the early 1930s, before Soviet authorities banned its use and replaced it with the civil law.