Imperial Gazetteer of India

A tribe is a collection of families bearing a common name, speaking a common dialect, occupying or professing to occupy a common territory and is not usually endogamous, though originally it might have been so.

Oxford Dictionary

A tribe is a group of people in a primitive or barbarous state of development acknowledging the authority of a chief and usually regarding themselves as having a common ancestor.

Ralph Linton

In its simplest form the tribe is a group of bands occupying a contiguous territory or territories and having a feeling of unity deriving from numerous similarities in culture, frequent contacts, and a certain commonality of interest.

Lucy Mair

A tribe is an independent political division of a population with a common culture.

G.W.B. Huntingford

A tribe is a group united by a common name in which the members take pride by a common language, by a common territory, and by a feeling that all who do not share this name are outsiders, ‘enemies’ in fact.

D.N. Majumdar

A tribe is a social group with territorial affiliation, endogamous, with no specialisation of functions, ruled by tribal officers, hereditary or otherwise, united in language or dialect, recognising social distance with other tribes or castes, without any social obloquy attaching to them, as it does in the caste structure, following tribal traditions, beliefs and customs,above all conscious of homogeneity of ethnic and territorial integration.

Lewis

Tribal societies are small in scale, are restricted in the spatial and temporal range of their social, legal, and political relations, and possess a morality, a religion, and a world view of corresponding dimensions. Characteristically too, tribal languages are unwritten, and hence, the extent of communication both in time and space inevitably narrow. At the same time, tribal societies exhibit a remarkable economy of design and have a compactness and self sufficiency lacking in modem society.

Majumdar and Madan :

1. In tribal India a tribe is definitely a territorial group; a tribe has a traditional territory, and emigrants always refer to it as their home.
2. All members of a tribe are not kin of each other, but within every Indian tribe kinship operates as a stong, associative regulative and integrating The consequence is tribal endogamy and the division of a tribe into clans and sub-clans and so on. These clans, etc., being kingroups, are exogamous.
3. Members of an Indian tribe speak one common langauge, their own or / and that oftheir neighbours. Intra-tribal conflict on a group scale is not a feature of Indian tribes. Joint ownership of property, wherever present, as for instance among the Hos, is not exclusive. Politically, Indian tribes are under the control of the State governments, But within a tribe there may be a number of Panchayats corresponding to the heterogeneity, racial and cultural, of the constituent population in a village or in adjacent villages.
4. There are other distinguishing features of Indian tribes.
   1. there are their dormitory institutions;
   2. the absence of institutional schooling for boys and girls;
   3. distinctive customs regarding birth, marriage, and death;
   4. a moral code different from that of Hindus and Muslims;
   5. peculiarities of religious beliefs and rituals which may distinguish tribesmen
      even from the low caste Hindus.