calumniate (v.)

mid-15c., "false accusation, slander," from Old French calomnie (15c.), from Latin calumnia "trickery, subterfuge, misrepresentation, malicious charge," from calvi "to trick, deceive."

According to de Vaan, PIE cognates include Greek kēlein "to bewitch, cast a spell," Gothic holon "to slander," Old Norse hol "praise, flattery," Old English hol "slander," holian "to betray," Old High German huolen "to deceive." The whole group is perhaps from the same root as call (v.). A doublet of challenge.

early 14c., chalenge, "something one can be accused of, a fault, blemish;" mid-14c., "false accusation, malicious charge; accusation of wrong-doing," also "act of laying claim" (to something), from Anglo-French chalenge, Old French chalonge "calumny, slander; demand, opposition," in legal use, "accusation, claim, dispute," from Anglo-French chalengier, Old French chalongier "to accuse, to dispute" (see challenge (v.)). The accusatory connotations faded 17c. The meanings "an objection" in law, etc.; "a calling to fight" are from mid-15c. The sense of "difficult task" is by 1954.