What is the X in X-mas?
c.1300, "holding of immovable property" (such as land or buildings,) from Anglo-French (late 13c.) and Old French tenement (12c.), from Medieval Latin tenementum "a holding, fief" (11c.), from Latin tenere "to hold" (see tenet). The meaning "dwelling place, residence" is attested from early 15c.; tenement house "house broken up into apartments, usually in a poor section of a city" is first recorded 1858, American English, from tenament in an earlier sense (especially in Scotland) "large house constructed to be let to a number of tenants" (1690s).