What is the X in X-mas?
1640s, "act of lubricating," noun of action from lubricate (v.). Earlier were lubifraction (1540s).
1620s, "to make slippery or smooth" (especially by the application of an oil), from Latin lubricatus, past participle of lubricare "to make slippery or smooth," from lubricus "slippery" (see lubricant (adj.)). Related: Lubricated; lubricating. Earlier verb was lubrify (1610s), from Medieval Latin lubrificare.