United Nations Working Group of Indigenous Population (WGIP), definition;

• (a) they are the descendants of groups, which were in the
  territory at the time when other groups of different cultures or ethnic
  origin arrived there;
• (b) precisely because of their isolation from other segments of
  the country's population they have almost preserved intact the customs
  and traditions of their ancestors which are similar to those
  characterised as indigenous;
• (c) they are, even if only formally, placed under a state
  structure which incorporates national, social and cultural
  characteristics alien to their own.

International Labor Organization (convention no. 169), definition;

both tribal peoples whose social, cultural and economic conditions
distinguish them from other sections of the national community and
whose status is regulated wholly or partially by their own customs or
traditions or by special laws or regulations, and to peoples who are
regarded as indigenous on account of their descent from the populations
which inhabit the country at the time of conquest or colonisation.


World Bank (operational directive 4.20, 1991), definition;

a) close attachment to ancestral territories and to the natural resources in these areas;

b) self-identification and identification by others as members of a distinct cultural group;

c) an indigenous language, often different from the national language;

d) presence of customary social and political institutions;

e) primarily subsistence-oriented production.

definitions by renowned organizations of the world on indigenous or janjatis, since u guys do not know the definitions, here u go.