The Adivasi (also spelled Adibasi) are the heterogeneous tribal groups across the Indian subcontinent. The term Adivasi, a 20th-century construct meaning "ancient inhabitants", is now widely used as a self-designation by many of the communities who are officially recognized as "Scheduled Tribes" in India and as "Ethnic minorities" in Bangladesh. They constitute approximately 8.6% of India's population (around 104.2 million, according to the 2011 Census) and about 1.1% of Bangladesh's population (roughly 2 million, 2010 estimate).

Claiming to be among the original inhabitants of the Indian subcontinent, many present-day Adivasi communities formed during the flourishing period of the Indus Valley Civilization or after the decline of the IVC, harboring various degrees of ancestry from ancient Dravidians, Indo-Aryan, Austroasiatic and Tibeto-Burman language speakers.

Adivasi studies is a new scholarly field, drawing upon archaeology, anthropology, agrarian history, environmental history, subaltern studies, indigenous studies, aboriginal studies, and developmental economics. It adds debates that are specific to the Indian context.

Adivasi is the collective term for the tribes of the Indian subcontinent, who are claimed to be the indigenous people of India. It refers to "any of various ethnic groups considered to be the original inhabitants of the Indian subcontinent". Although "Tribe" and "Adivasi" are often used interchangeably, they have distinct meanings. "Tribe" refers to a social unit, whereas "Adivasi" means ancient inhabitants. The former is an anthropological term primarily associated with the social characteristics, while the latter is a socio-political term associated with the autochthonous identity, specifically used in the Indian subcontinent. The use of the term Adivasi, as a socio-political construct, often overlooks the historical complexities of indigeneity, including migration, linguistics, anthropology, and archaeology—something Hardiman views as "the idea that Adivasis are autochthonous, or original, inhabitants is belied by the fact that many such groups are known to have migrated in recorded history into the areas in which they are now found, often displacing existing inhabitants in the process... There have been so many migrations in and out of this region in past centuries that no particular jati [community] can have genuine grounds for making such a claim."

The term Adivasi, in fact, is a Sanskrit word specifically coined in 1930s by the tribal political activists to give a distinct and collective indigenous identity to the tribals, alleging that Indo-Aryan and Dravidian ethnolinguistic group are not indigenous to the land. The term was initially popularized by tribal activist organizations in present-day Jharkhand. Later, Thakkar Bapa used the word to advocate for a pan-Indian reference to the inhabitants of forests, a usage that was later adopted, although not popularly by Gandhi. Post-independence, Jaipal Singh Munda, president of the Jharkhand-based organization 'Adivasi Mahasabha', was elected as an independent member representing tribals in the Constituent Assembly. He advocated for the term 'Adivasi' in place of 'Scheduled Tribe'. However, due to the need for legal connotation, Ambedkar rejected the use of such general socio-political terms in the Constitution by adopting 'Scheduled Tribe' for tribals and 'Scheduled Caste' for untouchables, although he advocated for Dalits. Ambedkar, responding to Munda's advocacy for 'Adivasi', clarified: "why I substituted the word "scheduled" for the word "aboriginal" the explanation is ... the word 'scheduled tribe' has a fixed meaning, because it enumerates the tribes ... the word 'Adibasi' is really a general term which has no specific legal de jure connotation, something like the Untouchables [Dalits]. Anybody may include anybody in the term 'untouchable' [and Adibasi]. ...by this Constitution, we are conferring certain privileges, certain rights on these Adibasis. In order that, if the matter was taken to a court of law there should be a precise definition as to who are these Adibasis, it was decided to invent, so to say, another category or another term to be called 'Scheduled tribes' and to enumerate the Adibasis under that head."

In most Indo-Aryan languages, such as Hindi and Bengali, Adivasi means "Original Inhabitants," Sanskritic derivation from ādi 'beginning, origin'; and vāsin 'dweller' (itself from vas 'to dwell'), thus literally meaning 'beginning inhabitant'. Although terms such as atavika, vanavāsi ("forest dwellers"), or girijan ("mountain people") are also used for the tribes of India, adivāsi carries the specific meaning of being the original and autochthonous inhabitants of a given region, and the self-designation of those tribal groups. However, the use and acceptance of the term Adivasi vary across places, communities, and contexts and do not always carry its original connotation. For instance tribals of North East India don't use the term Adivasi for themselves, rather prefer the word "Indigenous" or "Tribe". The term Adivāsi applies only to the immigrated Tea-tribes of Central India origin. In Bangladesh, Adivasi term is also used to refer tribals of Central India affiliation, although not popularly as India, wherein the tribals have designated as "Ethnic minorities" (Khudro Nritattik Jonogoshti). Similarly the term Adivasi Janjati used in Nepal for hierarchically lowly-status ethnic groups in Nepal's caste system, having own socio-cultural institutions, although the political context differed historically under the Shah and Rana dynasties. In Sri Lanka, the Vedda people are referred as Adivasi.

The Constitution of India doesn't use the word Adivasi, and directs government officials to not use the word in official work. The notified tribals are designated as Scheduled Tribes (Anusuchit Janjati) in the Constitution. The constitution of India grouped these ethnic groups together "as targets for social and economic development". Since that time the tribe of India have been known officially as Scheduled Tribes. Article 366 (25) defined scheduled tribes as "such tribes or tribal communities or parts of or groups within such tribes or tribal communities as are deemed under Article 342 to be Scheduled Tribes for the purposes of this constitution". But, due to the political leverage associated with tribals in the Constitution of India, the term Adivasi serves as a unifying factor both politically and socio-culturally, maintaining its influence in public discourse as a status quo, challenging the legally designated, state-specific administrative term Scheduled Tribes.

Judicially it remarked that "India is a country of old immigrants in which people have been coming in over the last ten thousand years or so...  who came mainly from the North-West, and to a lesser extent from the North-East...  At one time it was believed that the Dravidians were the original inhabitants. However, this view has been considerably modified subsequently, and now the generally accepted belief is that the original inhabitants of India were the pre-Dravidian aborigines, i.e. the ancestors of the present tribals or Adivasis (Scheduled Tribes)."