In linguistics, clusivity is a grammatical distinction between inclusive and exclusive first-person pronouns and verbal morphology, also called inclusive "we" and exclusive "we". Inclusive "we" specifically includes the addressee (that is, one of the words for "we" means "you and I and possibly others"), while exclusive "we" specifically excludes the addressee (that is, another word for "we" means "he/she/they and I, but not you"), regardless of who else may be involved. While imagining that this sort of distinction could be made in other persons (particularly the second) is straightforward, in fact the existence of second-person clusivity (you vs. you and they) in natural languages is controversial and not well attested. While clusivity is not a feature of standard English language, it is found in many languages around the world.
The first published description of the inclusive-exclusive distinction by a European linguist was in a description of languages of Peru in 1560 by Domingo de Santo Tomás in his Grammatica o arte de la lengua general de los indios de los Reynos del Perú, published in Valladolid, Spain.
Clusivity paradigms may be summarized as a two-by-two grid:
In some languages, the three first-person pronouns appear to be unrelated. That is the case for Chechen, which has singular so/со, exclusive txo/тхо, and inclusive vay/вай. In others, however, all three are related, as in Tok Pisin, an English creole spoken in Papua New Guinea, which has singular mi, exclusive mi-pela, and inclusive yu-mi (a compound of mi with yu "you") or yu-mi-pela. However, when only one of the plural pronouns is related to the singular, that may be the case for either one. In some dialects of Mandarin Chinese, for example, inclusive or exclusive 我們/我们 wǒmen is the plural form of singular wǒ "I", and inclusive 咱們/咱们 zánmen is a separate root. However, in Hadza, the inclusive, ’one-be’e, is the plural of the singular ’ono (’one-) "I", and the exclusive, ’oo-be’e, is a separate root.