Liminality, from the Latin limen, threshold, names the condition of being on a boundary: no longer what one was and not yet what one will become. The concept originates with Arnold van Gennep, whose Rites of Passage (1909) identified the threshold phase as the middle of three in every such rite, and it was developed into a general analytic tool by Victor Turner from the 1960s.
Turner's account describes the liminal phase largely by what is absent from it. The person in it has been stripped of status, name, clothing, rank and often of ordinary identity. They are ambiguous, because the classifications by which a society sorts people do not apply to them, and they are therefore treated as both dangerous and powerful, what has no category threatens the categories. Liminal persons are commonly secluded, subjected to ordeal, taught the community's secrets, and required to submit absolutely to those conducting the rite. Among themselves they experience communitas, the levelled and intense fellowship of people who have no status left to divide them.
Turner extended the concept well beyond rites of passage. He proposed "liminoid" for the optional, individual and often artistic analogues found in industrial societies, theatre, festival, sport, pilgrimage, the counterculture, distinguishing them from the obligatory liminality of a small-scale society's initiations, which one does not choose. And he identified permanently liminal roles: monastics, whose vows place them outside the ordinary structure of family and property; the mendicant; the court fool; the prophet; the outsider whose authority consists precisely in having no position.
The concept's value is that it names something otherwise difficult to see. It explains why threshold moments are ritually elaborated everywhere; why people in transition are treated as polluting and as sacred at the same time; why initiation so consistently involves symbolic death and rebirth; and why so many traditions locate religious authority in figures who have stepped outside the social structure rather than in those at its centre.
It has been criticised for the reasons that attach to any highly elastic concept. It is applied very widely, sometimes to any period of uncertainty whatever, and it can obscure the specific power relations operating within a rite, being stripped of status is not the same experience for everyone, and initiates are rarely in a position to refuse what is done to them. Feminist and postcolonial scholarship has pressed both points. The concept nonetheless remains among the most productive in the study of ritual and has been taken up well beyond it, in literary studies, political theory and organisational research.