• synonyms


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.
Show More

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 of umbo

  • 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


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
Show More
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

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

Show More
Online Etymology Dictionary, © 2010 Douglas Harper

umbo in Medicine


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.
Show More
Related formsumbo•nal (ŭmbə-nəl, ŭm-bōnəl) null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.