T–V distinction
Definition - The use of second-person pronouns to distinguish different levels of formality. For example, French speakers refer to their interlocutors with tu when speaking informally and vous when speaking formally.

Etymology -
The term was introduced in 1960 by R. Brown and A. Gilman in The Pronouns of Power and Solidarity in American Anthropologist [4 (6): 24–39]. The T and V refer to the initial letters of the Latin pronouns tu and vos.

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