What is the X in X-mas?
1803, from Modern Latin scarlatina (Sydenham, 1676), from Italian scarlattina (Lancelotti, 1527), fem. of scarlattino (adj.), diminutive of scarlatto "scarlet" (see scarlet). It is a synonym for scarlet fever, not a milder form of it. Related: Scarlattinal.
scarlatina scar·la·ti·na (skär'lə-tē'nə)
See scarlet fever.