Coven or covan was originally a late medieval Scots word (c1500) meaning a gathering of any kind, according to the Oxford English Dictionary. It derives from the Latin root word convenire meaning to come together or to gather, which also gave rise to the English word convene.
The word coven remained largely unused in English until 1921 when Margaret Murray promoted the idea, now much disputed, that all witches across Europe met in groups of thirteen which they called 'covens'.
The number of persons involved may vary. Although thirteen has been suggested as the optimum number (probably in deference to Murray's theories), any number above and including three can be a coven. Two would usually be referred to as a working couple (in any combination of sexes.) Within the community, many believe that a coven larger than thirteen is unwieldy, citing unwieldy group dynamics and an unfair burden on the leadership. When a coven has grown too large to be manageable, it may split, or "hive". In Wicca this may also occur when a newly made High Priest or High Priestess, also called 3rd Degree ordination, leaves to start their own coven. Wiccan covens are generally jointly led by a High Priestess and a High Priest, though some are led by only one or the other. In more recent forms of neopagan witchcraft, covens are sometimes run as democracies with a rotating leadership.
An intermediate view is often portrayed in fantasy stories and popular culture. In this usage, a coven is a gathering of witches to work spells in tandem. Such imagery can be traced back to Renaissance prints depicting witches and to the three 'weird sisters' in Shakespeare's play Macbeth. More orgiastic witches' meetings are also depicted in Robert Burns' poem Tam o' Shanter and in Goethe's play Faust. Movie portrayals have included, for example, Rosemary's Baby, The Covenant, Underworld (2003 film) and Underworld: Evolution , The Craft and COVEN. In television, covens were portrayed in the U.S. supernatural drama, Charmed''.
Coven can be a term used to describe a group or community of Sanguinarians, especially those who communicate only over the internet. Its origins almost certainly come from the Wiccan usage of coven.