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umbo

[uhm-boh]
noun, plural um·bo·nes [uhm-boh-neez] /ʌmˈboʊ niz/, um·bos.
  1. a boss on a shield, as one at the center of a circular shield.
  2. any similar boss or protuberance.
  3. Zoology. the beak of a bivalve shell; the protuberance of each valve above the hinge.
  4. Anatomy. the depressed area on the outer surface of the tympanic membrane.
  5. 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)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for umbo

Historical Examples

  • Umbonata, having an umbo or conical projection like the boss of a shield.

    The Mushroom, Edible and Otherwise

    M. E. Hard

  • It is by the position of the umbo in the grave that this fact has been exactly ascertained.

  • The centre was formed of metal, and was called a boss or umbo.

  • The summit or apex of the valve is called the umbo, or beak.

    The Sea-beach at Ebb-tide

    Augusta Foote Arnold

  • Umbonate, bossed; furnished with a low, rounded projection like a boss (umbo).

British Dictionary definitions for umbo

umbo

noun plural umbones (ʌmˈbəʊniːz) or umbos
  1. a small hump projecting from the centre of the cap in certain mushrooms
  2. a hooked prominence occurring at the apex of each half of the shell of a bivalve mollusc
  3. anatomy the slightly convex area at the centre of the outer surface of the eardrum, where the malleus is attached on the internal surface
  4. a large projecting central boss on a shield, esp on a Saxon shield
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Derived Formsumbonate (ˈʌmbənɪt, -ˌneɪt), umbonal (ˈʌmbənəl) or 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

Word Origin and History for umbo

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

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Online Etymology Dictionary, © 2010 Douglas Harper
umbo in Medicine

umbo

(ŭm′bō)
n. pl. um•bos
  1. 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.
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Related formsum′bo•nal (ŭm′bə-nəl, ŭm-bō′nəl) null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.