\Scu"tum\, n.; pl. {Scuta}. [L.] 1. (Rom. Antiq.) An oblong shield made of boards or wickerwork covered with leather, with sometimes an iron rim; -- carried chiefly by the heavy-armed infantry. 2. (O. Eng. Law) A penthouse or awning. [Obs.] --Burrill. 3. (Zo["o]l.) (a) The second and largest of the four parts forming the upper surface of a thoracic segment of an insect. It is preceded by the prescutum and followed by the scutellum. See the Illust. under {Thorax}. (b) One of the two lower valves of the operculum of a barnacle.