Definition of "Quartodeciman"

Any of a group of early Christians (especially in Asia Minor, Syria, and Jerusalem) who observed Pascha (Christian Passover or Easter) on Nisan 14 of the Hebrew calendar, the day Jesus was crucified according to the Gospel of John, and the day before the beginning of Jewish Passover (also called the Feast of Unleavened Bread (מַצּוֹת (matsót)), which began on Nisan 15.  examples

Of or pertaining to these people.  examples