umbo

[ uhm-boh ]

/ ˈʌm boʊ /

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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.

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Origin of umbo

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

Words nearby umbo

umbilication, umbilicus, umbiliform, umble pie, umbles, umbo, umbonal, umbonate, umbra, umbrage, umbrageous

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use umbo in a sentence

One species (C. discors) is pale green, with radiating lines from umbo to margin.
The Sea Shore|William S. Furneaux
The hand was protected by a hollow conical boss or umbo, fixed to the wood by its brim, but projecting considerably.
Beowulf|R. W. Chambers
It is a light pelagic form, with paper-like plates and angularly bent carina, with a prominent umbo.
Journal of Entomology and Zoology: Volume 6, Number 4, December 1914|Various
One is in the Spanish-Moorish style and of a convex shape, with iron bordering and umbo, and a lining of yellow brocade.
The Arts and Crafts of Older Spain, Volume I (of 3)|Leonard Williams

The paracentesis knife is inserted boldly through the membrane a little behind and above the umbo.
A System of Operative Surgery, Volume IV (of 4)|Various

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 forms of umbo

umbonate (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