Word Origin & History
1530s, "one who baptizes over again," from L. anabaptismus "second baptism" (used in literal sense from 4c.), as if from Gk. ana- "up (in place or time), back again, anew" + baptismos "baptism." Originally in Eng. in ref. to sect that practiced adult baptism and arose in Germany 1521. Probably so called
because, as a new faith, they baptized converts who had already been baptized (as infants) in the older Christian churches. Modern branches only baptize once (adults) and do not actively seek converts. The name also was applied, usually opprobriously, to Baptists, perhaps due to the multiple immersions of their baptisms.