What is the X in X-mas?
c.1400, from Middle French massif "bulky, solid," from Old French masse "lump" (see mass (n.1)). Related: Massively; massiveness. U.S. Cold War strategy of massive retaliation was introduced by J.F. Dulles in early 1954.
massive mas·sive (mās'ĭv)
Large in comparison with the usual amount.
Affecting a large area of bodily tissue; widespread and severe.