ca·lum·ni·ous \-nēəs\adjective Etymology: Middle French or Late Latin; Middle French calomnieux, from Late Latin calumniosus full of trickery, from Latin calumnia trickery, calumny + -osus -ous : given to calumny < calumnious backbiting rivals > : constituting or marked by calumny < hurt by calumnious reports > : slanderous