Other forms: covens
A group of witches is called a coven. In books, a coven of witches often gather at night to make potions and cast spells.
The mythology of witches has them meeting under cover of night, often in mysterious groups of 13. Although there are only three of them, the "weird sisters" in Shakespeare's play "Macbeth" could be considered a coven. To people who follow the contemporary religion called Wicca, a coven is a gathering, no different from a congregation in Christianity. The word coven arose in the mid-1600s, ultimately from the Latin root conventus, "assembly."