What does "conventicle" mean?

Conventicle: An assembly for religious worship; esp., such an assembly held privately, as in times of persecution, by Nonconformists or Dissenters in England, or by Covenanters in Scotland; -- often used opprobriously, as if those assembled were heretics or schismatics. The first Christians could never have had recourse to nocturnal or clandestine conventicles till driven to them by the violence of persecution. Hammond. A sort of men who . . . attend its [the curch of England's] service in the morning, and go with their wives to a conventicle in the afternoon. Swift.