Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The boss or knob at the center of a shield.
  • noun Biology A knoblike protuberance arising from a surface, as the prominence near the hinge of a bivalve shell or the raised area in the center of the cap of a mushroom.
  • noun Anatomy A small projection at the center of the outer surface of the eardrum.

from The Century Dictionary.

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

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun biology 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.
  • noun zoology One of the lateral prominence just above the hinge of a bivalve shell.
  • noun mycology A bump or protrusion on the top of the cap.
  • noun historical The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.

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

  • noun a slight rounded elevation where the malleus attaches to the eardrum

Etymologies

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

[Latin umbō, umbōn-; see nobh- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

Borrowed from Latin umbo

Examples

  • Running upward and slightly forward from the umbo is a reddish-yellow streak produced by the manubrium of the malleus.

    XII. Surface Anatomy and Surface Markings. 2. Surface Markings of Special Regions of the Head and Neck

  • For example, these bivalve shells, probably arks (Arcidae), each had a hole thru its umbo.

    Archive 2009-04-01

  • For example, these bivalve shells, probably arks Arcidae, each had a hole thru its umbo.

    Indian shell tools from Florida

  • The above magnified picture was taken from below the varix; the umbo was towards the top.

    Lessons learned from a specimen of Spisula solidissima

  • The above magnified picture was taken from below the varix; the umbo was towards the top.

    Archive 2007-10-01

  • The Romans called the point at which the cord connecting the fetus with the placenta was cut and tied off the umbilicus, from umbo, “knob, projection.”

    No Uncertain Terms

  • The Romans called the point at which the cord connecting the fetus with the placenta was cut and tied off the umbilicus, from umbo, “knob, projection.”

    No Uncertain Terms

  • The Romans called the point at which the cord connecting the fetus with the placenta was cut and tied off the umbilicus, from umbo, “knob, projection.”

    No Uncertain Terms

  • Their coverings having now been removed, on each shield a carving of the head of Caesar could be seen on the umbo, or central knob.

    Herodias

  • The Romans called the point at which the cord connecting the fetus with the placenta was cut and tied off the umbilicus, from umbo, “knob, projection.”

    No Uncertain Terms

Comments

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  • 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

  • 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