degenerative (adj.)

late 15c., "having lost or suffered impairment to the qualities proper to the race or kind," 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 "off, away from" (see de-) + genus (genitive generis) "birth, descent" (from PIE root *gene- "give birth, beget").

Of things, "unworthy, debased, having fallen in quality or passed to an inferior state," from 1550s. The noun, "one who has degenerated," is from 1550s. Related: Degenerately; degenerateness.