Main Entry: um·bo

Pronunciation: \ˈəm-(ˌ)bō\

Function: noun

Inflected Form(s): plural um·bo·nes \ˌəm-ˈbō-(ˌ)nēz\ or umbos

Etymology: Latin; akin to Latin umbilicus — more at navel

Date: 1721

1 : the boss of a shield
2 : a rounded elevation: as a : an inward projection of the tympanic membrane of the ear b : one of the lateral prominences just above the hinge of a bivalve shell

— um·bo·nal \ˈəm-bə-n^əl, ˌəm-ˈbō-\ adjective

— um·bo·nate \ˈəm-bə-ˌnāt, ˌəm-ˈbō-nət\ adjective

[umbo illustration]