What is the X in X-mas?
early 15c., "pertaining to sclerosis," from medical Latin scleroticus, from Greek skleroun (see sclerosis). Figurative meaning "unchanging, rigid" is from 1961.
sclerotic scle·rot·ic (sklə-rŏt'ĭk)adj.
Affected or marked by sclerosis.
Of or relating to the sclera of the eye.