umbo

The boss or knob at the center of a shield.

A knoblike protuberance arising from a surface, as the prominence near the hinge of a bivalve shell or the raised area in the center of the cap of a mushroom.

A small projection at the center of the outer surface of the eardrum.

The boss of a shield, central in the case of a circular shield.

A boss or knob.

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

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.

A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane; as, the umbo in the integument of the larvæ of echinoderms or in the tympanic membrane of the ear.