umbo — English Dictionary

Noun

1. The boss of a shield, at or near the middle and usually projecting, sometimes in a sharp spike.

   Usage

   • Historical

   Examples

   It is thirteen inches diameter, made of wood covered with leather, and an iron plate decorated with nails and mouldings; the boss or umbo projects four inches.

   serves as the umbo of the region’s so-called Silicon Shield

2. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane. An inward projection of the tympanic membrane of the ear.

3. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane. One of the lateral prominences just above the hinge of a bivalve shell.

4. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane. A bump or protrusion on the cap of a mushroom or toadstool.

Noun

1. a slight rounded elevation where the malleus attaches to the eardrum

   Broader terms

   convex shapeconvexity