Terminology Tuesday: Quartodecimanism
The belief of a number of early Christians in Asia Minor that Easter should be observed on the fourteenth Nisan, irrespective of the day of the week that may happen to be. In contrast, the Western church determined at the Council of Nicea (A.D. 325) that the crucifixion should be commemorated on the Friday of the week, whether or not it fell on the fourteenth, and the resurrection on the following Lord’s day.
Cairns, A. (2002). In Dictionary of Theological Terms (p. 358). Belfast; Greenville, SC: Ambassador Emerald International.