Isan language in the context of "Isan"

Thai, or Central Thai (historically Siamese; Thai: ภาษาไทย), is a Tai language of the Kra–Dai language family spoken by the Central Thai, Mon, Lao Wiang, and Phuan people in Central Thailand and the vast majority of Thai Chinese enclaves throughout the country. It is the sole official language of Thailand.

Thai is the most spoken of over 60 languages of Thailand by both number of native and overall speakers. Over half of its vocabulary is derived from or borrowed from Pali, Sanskrit, Mon and Old Khmer. It is a tonal and analytic language. Thai has a complex orthography and system of relational markers. Spoken Thai, depending on standard sociolinguistic factors such as age, gender, class, spatial proximity, and the urban/rural divide, is partly mutually intelligible with Lao, Isan, and some fellow Thai topolects. These languages are written with slightly different scripts, but are linguistically similar and effectively form a dialect continuum.

Lao (ພາສາລາວ, [pʰáː.sǎː láːw]), sometimes referred to as Laotian, is the official language of Laos and a significant language in the Isan region of northeastern Thailand, where it is usually referred to as the Isan language. Spoken by over 3 million people in Laos and 3.7 million in all countries, it serves as a vital link in the cultural and social fabric of these areas. It is written in the Lao script, an abugida that evolved from ancient Tai scripts.

Lao is a tonal language, where the pitch or tone of a word can alter its meaning, and is analytic, forming sentences through the combination of individual words without inflection. These features, common in Kra-Dai languages, also bear similarities to Sino-Tibetan languages like Chinese or Austroasiatic languages like Vietnamese. Lao's mutual intelligibility with Thai and Isan, fellow Southwestern Tai languages, allows for effective intercommunication among their speakers, despite differences in script and regional variations.

The Southwestern Tai or Thai languages are a branch of the Tai languages of Southeast Asia. Its languages include Central Thai (Siamese), Northern Thai (Lanna), Lao (including Isan), Shan and others.