Kelantan-Pattani Malay (bahasa Melayu Kelantan/Patani; ภาษายาวี; baso Taning in Pattani; kecek Klate in Kelantan) is an Austronesian language of the Malayic subfamily spoken in the Malaysian state Kelantan, Besut and Setiu in Terengganu, and the southernmost provinces of Thailand. It is the primary spoken language of Thai Malays, but is also used as a lingua franca by ethnic Southern Thais in rural areas, Muslim and non-Muslim and the Sam-Sam, a mostly Thai-speaking population of mixed Malay and Thai ancestry.
Kelantan-Pattani Malay is highly divergent from other Malay varieties because of its geographical isolation from the rest of the Malay world by high mountains, deep rainforests and the Gulf of Thailand. In Thailand, it is also influenced by Thai.
Kelantanese-Pattani Malay is distinct enough that radio broadcasts in Standard Malay cannot be understood easily by native speakers of Kelantan-Pattani Malay, such as those in Thailand, who are not taught the standard variety of the language. Unlike Malaysia where Standard Malay is compulsory in the school curriculum, no one is required to learn Standard Malay in Thailand and so there is potentially less language influence from Standard Malay but potentially more from Thai. It is also distinct from Kedah Malay, Pahang Malay and Terengganu Malay, but those languages are much more closely related to the Kelantanese-Pattani Malay language.
The language is often referred to in Thai as (ภาษายาวี; phāːsǎː jāːwīː), which is a corruption of the Malay name for the modified Arabic alphabet for writing Malay, Jawi (Jawi: جاوي; ɟaˈwi). It is also referred to in Thai as (ภาษามลายูปัตตานี; phāːsǎː mālāːjūː pàttāːnīː) and similarly locally in Malay as bahasa Melayu Patani (Jawi: بهاس ملايو ڤطاني, Rumi: bahasa Melayu Patani, baˈsɔ ˈnːaju ˈtːaniŋ). The language is often simply just called in Pattani.
Kelantanese is known in Standard Malay as bahasa Kelantan, and in Kelantanese as baso Kelate. It is also known as baso Besut or Kecek Kelate-Besut in Besut and Setiu of Terengganu State.