umbo

noun

um·​bo ˈəm-(ˌ)bō 

plural umbones ˌəm-ˈbō-(ˌ)nēz  or umbos

1

: the boss of a shield

2

: a rounded elevation: such 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

umbonal

ˈəm-bə-nᵊl  ˌəm-ˈbō- 

adjective

umbonate

ˈəm-bə-ˌnāt  ˌəm-ˈbō-nət 

adjective

Illustration of umbo

• U umbo 1

Examples of umbo in a Sentence

Recent Examples on the Web

Another unique burial held a warrior, buried with his shield umbo, a sword and suspension chain and a spearhead. —Irene Wright, Miami Herald, 30 Apr. 2025

The mic is designed to be implanted inside the middle ear, with its triangular tip resting against part of the eardrum known as the umbo. —Ben Coxworth, New Atlas, 19 July 2024

Word History

Etymology

borrowed from Latin umbōn-, umbō "boss of a shield, protuberance, projecting piece of land," going back to Indo-European *h₃n̥b^h-on- or * h₃enb^h-on-, derivative, with the vowel in a different position ("floating ablaut," German Schwebeablaut), from the base seen in *h₃nob^h- "hub of a wheel, nave entry 1"

Note: A likely cognate is Old High German amban, ampan "belly of a pig, paunch," a masculine strong noun, though more closely parallel to Latin are traces of an n-stem: a single late Franconian form ambin, presumably dative of a masculine n-stem *ambo; and Old Saxon ambon "paunch" (Latin abdomina), accusative plural of a presumed n-stem *ambo.

First Known Use

1721, in the meaning defined at sense 1

Medical Definition

umbo

noun

um·​bo ˈəm-(ˌ)bō 

plural umbones ˌəm-ˈbō-(ˌ)nēz  or umbos

: an elevation in the tympanic membrane of the ear