1606, from Fr.
férocité, from L.
ferocitatem (nom.
ferocitas) "fierceness," from
ferocis, an oblique case of
ferox "fierce, wild-looking," a derivative of
ferus "wild" (see
fierce) +
-ox, -ocem (gen.
-ocis), a suffix meaning "looking or appearing" (cognate with Gk.
ops "eye, sight").
Ferocious is first recorded 1646.