Definition of umbos:
(n) :
(historical) The boss of a shield, at or near the middle and usually projecting, sometimes in a sharp spike.
(n) :
(biology) A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane.
(n) :
(anatomy) An inward projection of the tympanic membrane of the ear.
(n) :
(zoology) One of the lateral prominences just above the hinge of a bivalve shell.
(n) :
(mycology) A bump or protrusion on the cap of a mushroom or toadstool.