Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The boss or knob at the center of a shield.
  • n. Biology A knoblike protuberance arising from a surface, as the prominence near the hinge of a bivalve shell or the projection at the scale tip of a seed-bearing cone.
  • n. Anatomy A small projection at the center of the outer surface of the eardrum.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane; as, the umbo in the integument of the larvæ of echinoderms or in the tympanic membrane of the ear.
  • n. One of the lateral prominence just above the hinge of a bivalve shell.
  • n. A bump or protrusion on the top of the cap.
  • n. The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.

from the GNU version of the Collaborative International Dictionary of English

  • n. The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.
  • n. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane.
  • n. One of the lateral prominences just above the hinge of a bivalve shell.

from The Century Dictionary and Cyclopedia

  • n. The boss of a shield, central in the case of a circular shield.
  • n. A boss or knob.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a slight rounded elevation where the malleus attaches to the eardrum

Etymologies

Latin umbō, umbōn-; see nobh- in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Borrowed from Latin umbo (Wiktionary)

Examples

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Comments

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  • A mogul's what skiers call a hump -
    A term for a glorified bump.
    The kids like them jumbo
    But I'll take an umbo -
    Content with a notional jump.

    December 16, 2014

  • 1. a boss on a shield, as one at the center of a circular shield, or any similar boss or protuberance.
    2. in zoology, the beak of a bivalve shell; the protuberance of each valve above the hinge.
    3. in anatomy, the depressed area on the outer surface of the tympanic membrane.
    4. a blunt or rounded protuberance arising from a surface, as on a pine cone scale.

    Etymologically related, not surprisingly, to umbilicus.

    March 27, 2007