The Collaborative International Dictionary of English v.0.48:

Scutum \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.
      [1913 Webster]

   2. (O. Eng. Law) A penthouse or awning. [Obs.] --Burrill.
      [1913 Webster]

   3. (Zool.)
      (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.
          [1913 Webster]