Lewis Short
(adjective) : spĕcŭlātōrĭus, a, um, speculator
* Of or belonging to spies or scouts: navigia,spy-boats, vessels of observation,Caes. B. G. 4, 26; also called speculatoriae naves,Liv. 30, 10, 14; 35, 26, 9; 36, 42, 8; and caliga, worn by spies or scouts, Suet. Calig. 52.— Hence, subst.: spĕcŭlātōrĭa, ae, f.
* (Sc. navis.) A spy-boat, Liv. 22, 19, 5; 22, 36, 42.
* (Sc. caliga.) A boot worn by spies or scouts, Tert. Cor. Mil. 1.
Charlton T. Lewis, Charles Short, A Latin Dictionary