Kinship terminology refers to the various systems used in languages to refer to the persons to whom an individual is related through kinship. Different societies classify kinship relations differently and therefore use different systems of kinship terminology - for example some languages distinguish between affinal and consanguine uncles, whereas others have only one word to refer to both a father and his brothers. Kinship terminologies include the terms of address used in different languages or communities for different relatives and the terms of reference used to identify the relationship of these relatives to ego or to each other.

Anthropologist Lewis Henry Morgan (1818–1881) performed the first survey of kinship terminologies in use around the world. Though much of his work is now considered dated, he argued that kinship terminologies reflect different sets of distinctions. For example, most kinship terminologies distinguish between sexes (the difference between a brother and a sister) and between generations (the difference between a child and a parent). Moreover, he argued, kinship terminologies distinguish between relatives by blood and marriage (although recently some anthropologists have argued that many societies define kinship in terms other than blood).

Robert Castel (born August 1, 1933, Saint-Pierre-Quilbignon (today in Brest)) is a French sociologist, currently a researcher at the École des hautes études en sciences sociales.

His initial works dealt with the notion or object of the 'psy' sciences then with what he calls the 'new social questions'. In the 1960s he worked with Pierre Bourdieu. He then became interested in psychoanalysis and psychiatry, establishing a critical sociology of these issues and linking this work to Michel Foucault, particularly to his 'genealogical approach'. His later works dealt with exclusion, or rather what he calls the 'disaffiliation', which affects individuals 'by default'.

His current works examine how the wage system, which at first was despised, has gradually established itself as the reference model and has been progressively associated with social protections, and the concept of social property, creating a constitutive status of 'social identity'. He is responsible for the formation of Le Groupe d'analyse du social et de la sociabilité (GRASS), a specialised group of sociologists within the CNRS.