Here are two explanations of the derivation of the word “Christmas.”

1. The word Christ stems from the Middle and Old English word Crist meaning the anointed one, the Lord’s Anointed.

It is borrowed from the Latin Christus and from the Greek Christos also meaning the anointed one. The Greek is a translation of Hebrew mashiach meaning anointed of the Lord or Messiah. In the word Christmas, the suffix -mas evolves from the Old English word maesse meaning festival, feast day or mass.

And from Wikipedia:

 2. Christmas derivative of Christ and Mass.

Mass is the term used of the celebration of the Eucharist in the Latin rites of the Roman Catholic Church. The word itself is derived from the phrase with which the liturgical celebration concludes in Latin, Ite, missa est. In this phrase, the word missa is usually explained as late Latin for classical Latin missio…