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[uhm-boh] /ˈʌm boʊ/
noun, plural umbones
[uhm-boh-neez] /ʌmˈboʊ niz/ (Show IPA),
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.
Origin of umbo
1715-25; < Latin umbō boss (of a shield), knob, projecting part; akin to umbilīcus (see umbilicus) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for umbo


noun (pl) umbones (ʌmˈbəʊniːz), 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
umbonate (ˈʌmbənɪt; -ˌneɪt), umbonal (ˈʌmbənəl), umbonic (ʌmˈbɒnɪk) adjective
Word Origin
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
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Word Origin and History for umbo

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

Online Etymology Dictionary, © 2010 Douglas Harper
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umbo in Medicine

umbo um·bo (ŭm'bō)
n. pl. um·bos or um·bo·nes (ŭm-bō'nēz)
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.

um'bo·nal (ŭm'bə-nəl, ŭm-bō'nəl) or um·bon'ic (ŭm-bŏn'ĭk) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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