umbo

[ uhm-boh ]

/ ˈʌm boʊ /

noun, plural um·bo·nes [uhm-boh-neez] /ʌmˈboʊ niz/, um·bos.

a boss on a shield, as one at the center of a circular shield.

any similar boss or protuberance.

Zoology. the beak of a bivalve shell; the protuberance of each valve above the hinge.

Anatomy. the depressed area on the outer surface of the tympanic membrane.

a blunt or rounded protuberance arising from a surface, as on a pine cone scale.

Nearby words

umbilication, umbilicus, umbiliform, umble pie, umbles, umbo, umbonal, umbonate, umbones, umbonic, umbra

Origin of umbo

1715–25; < Latin umbō boss (of a shield), knob, projecting part; akin to umbilīcus (see umbilicus)

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for umbo

I have applied this term to the oblique descent made by the umbo, towards the basal extremity of the anterior side of bivalves.
Zoological Illustrations, Volume III|William Swainson
The cuticle is smoky olive to fuliginous, darker when young, becoming paler as the pileus expands, but always darker on the umbo.
Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.|George Francis Atkinson
The umbo projects a little over the scutal margin of the terga.
A Monograph on the Sub-class Cirripedia (Volume 1 of 2)|Charles Darwin
Carina much bent, with the umbo placed at barely one third of the entire length of the valve from the apex.
A Monograph on the Sub-class Cirripedia (Volume 1 of 2)|Charles Darwin

The umbo here is invariably dorsal, the seed-wing invariably articulate.
The Genus Pinus|George Russell Shaw

British Dictionary definitions for umbo

umbo

/ (ˈʌmbəʊ) /

noun plural umbones (ʌmˈbəʊniːz) or umbos

a small hump projecting from the centre of the cap in certain mushrooms

a hooked prominence occurring at the apex of each half of the shell of a bivalve mollusc

anatomy the slightly convex area at the centre of the outer surface of the eardrum, where the malleus is attached on the internal surface

a large projecting central boss on a shield, esp on a Saxon shield

Derived Formsumbonate (ˈʌmbənɪt, -ˌneɪt), umbonal (ˈʌmbənəl) or umbonic (ʌmˈbɒnɪk), adjective

Word Origin for umbo

C18: from Latin: boss of a shield, projecting piece

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for umbo

umbo

1921, from Latin umbo "shield-boss, knob, projection."

Medicine definitions for umbo

umbo

[ ŭm′bō ]

n. pl. um•bos

A small anatomical projection on a surface, such as that on the inner surface of the tympanic membrane at the end of the manubrium of the malleus, corresponding to the most depressed point of the membrane.

Related formsum′bo•nal (ŭm′bə-nəl, ŭm-bō′nəl) null adj.