The term is "Anabaptist", and it refers to the general belief that there is no restriction to one baptism for the forgiveness of sins, which is a polemical charge leveled against some of the more radical Protestant groups during the Reformation. Thus, in Voltaire's Candide, when he has an Anabaptist drown it's a pretty funny joke.

The majority of Anabaptists in the US are Amish or Mennonite. There is no direct link to the various Baptist churches.