Scutum

from The Century Dictionary.

• noun In botany, the broad expansion of the style in plants of the milkweed family, especially in Stapelia.
• noun In Roman antiquity, a large oblong shield of heavy-armed Roman legionaries, as distinguished from the small round shield, or clypeus.
• noun In anatomy, the knee pan; the rotula or patella. See cut under knee-joint.
• noun In zoöl, a plate, shield, buckler, or some similar part; a large scale; a scute; a scutellum; especially, some piece of dermal armor or exoskeletal formation, as one of the bony plates of a sturgeon or a crocodile, a piece of the shell of a turtle, a ring or plate of an armadillo, one of the great scales of a pangolin, the frontal shield of a coot, etc. See cuts under Acipenser, armadillo, carapace, coot, crocodile, pangolin, and shield.
• noun In old law, a penthouse or awning.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.
• noun (O. Eng. Law), obsolete A penthouse or awning.
• noun 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.
• noun One of the two lower valves of the operculum of a barnacle.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun astronomy A small autumn constellation of the northern sky, said to resemble a shield. It lies between the constellations of Aquila, Sagittarius, and the tail of Serpens.