What is the X in X-mas?
late 15c., from Latin degeneratus, past participle of degenerare "to be inferior to one's ancestors, to become unlike one's race or kind, fall from ancestral quality," used of physical as well as moral qualities, from phrase de genere, from de + genus (genitive generis) "birth, descent" (see genus). The noun is from 1550s.
1540s, from Latin degeneratus, past participle of degenerare "fall from ancestral quality" (see degenerate (adj.)). Figurative sense of "to fall off, decline" was in Latin. Related: Degenerated; degenerating.
degenerate de·gen·er·ate (dĭ-jěn'ər-ĭt)
Characterized by degeneration, as of tissue, a cell, or an organ.
Having lost one or more highly developed functions, characteristics, or structures through evolution.