ˌ ̷ ̷(ˌ) ̷ ̷ˈdesəmən noun
( -s )
Etymology: Late Latin quartodecimanus, from Latin quartus decimus fourteenth (from quartus fourth + decimus tenth) + -anus -an; akin to Latin quattuor four — more at four , dime
1. usually capitalized : one of a group in the early church especially in Asia Minor who during the 2d century and until the Nicene council in 325 observed Easter on the 14th of Nisan when the Jews slaughtered the Passover lamb no matter on what day of the week that date occurred
2. : one of the Celtic Christians in the British Isles in the 7th century who followed a different mode of calculating the date of Easter from that used on the continent