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