What is the X in X-mas?
1828, "sacred choral song," from German Choral "metrical hymn in Reformed church," shortened from Choralgesang "choral song," translating Medieval Latin cantus choralis, from Latin cantus (see chant (v.)) + choralis (see choral). The -e was added to indicate stress. Meaning "group of singers" is 1942.
metrical hymn tune associated in common English usage with the Lutheran church in Germany. From early in the Reformation, chorales were to be sung by the congregation during the Protestant liturgy. Unison singing was the rule of the reformed churches, both in Germany and in other countries. Early polyphonic (multivoiced) versions may have been intended for a choir singing only the melody while the full version was played on the organ. In later polyphonic arrangements the melody shifted gradually to the treble line from its original position in the tenor