c.1325 (implied in
viciously), "of the nature of vice, wicked," from Anglo-Fr.
vicious, O.Fr.
vicieus, from L.
vitiosus "faulty, defective, corrupt," from
vitium "fault" (see
vice (1)). Meaning "inclined to be savage or dangerous" is first recorded 1711 (originally of animals, especially horses); that of "full of spite, bitter, severe" is from 1825. In law, "marred by some inherent fault" (1393), hence also this sense in logic (1605); cf.
vicious circle in reasoning (c.1792), which was given a general sense of "a situation in which action and reaction intensify one another" by 1839.