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n. pl. um·bo·nes (ŭm-bō′nēz) or um·bos
1. The boss or knob at the center of a shield.
a. 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.
b. Anatomy A small projection at the center of the outer surface of the eardrum.

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

um′bo·nal (ŭm′bə-nəl, ŭm-bō′nəl) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


n, pl umbones (ʌmˈbəʊniːz) or umbos
1. (Botany) a small hump projecting from the centre of the cap in certain mushrooms
2. (Zoology) a hooked prominence occurring at the apex of each half of the shell of a bivalve mollusc
3. (Anatomy) 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. (Arms & Armour (excluding Firearms)) a large projecting central boss on a shield, esp on a Saxon shield
[C18: from Latin: boss of a shield, projecting piece]
umbonate, umbonal, umbonic adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈʌm boʊ)

n., pl. um•bo•nes (ʌmˈboʊ niz) um•bos.
1. a boss on a shield.
2. any similar boss or protuberance.
3. the beak of a bivalve shell; the protuberance of each valve above the hinge.
4. the raised area on the inner surface of the tympanic membrane, where the malleus is attached.
[1715–25; < Latin umbō; akin to umbilīcus (see umbilicus)]
um′bo•nal (-bə nl) adj.
um′bo•nate (-nɪt, -ˌneɪt) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.umbo - a slight rounded elevation where the malleus attaches to the eardrumumbo - a slight rounded elevation where the malleus attaches to the eardrum
eardrum, myringa, tympanic membrane, tympanum - the membrane in the ear that vibrates to sound
convex shape, convexity - a shape that curves or bulges outward
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in classic literature ?
On a day, so far back that there was no way of estimating its distance, one, Somo, son of Loti, who was the chief of the island fortress of Umbo, had quarrelled with his father and fled from his wrath along with a dozen canoe-loads of young men.
Scallop counts were standardized to individuals per square meter and the shell height (distance from the umbo to the front of the shell in mm) of each scallop with a complete, visible length was measured using Image Pro Plus software.
Umbo from Kathore, along with their team established a one-day camp at Kathore.
A PhD student at the University of Massachusetts Amherst and researcher with the state's Cooperative Fish and Wildlife Research Unit, Skorupa puzzles out the species of each mussel, one at a time, notching her fingers along its prominently curved umbo, then drops the most common species, the eastern elliptio, back into the water.
The incision was deepened to the bone and elevated medially and inferiorly up to the fibrous annulus of the tympanic membrane and the tympanic membrane was reflected inferiorly up to the umbo. This exposes the attic, protympanum, retrotympanum and some part of mesotympanum revealing the ossicular chain.
fallax has more robust basidiomata, the pileus is larger (30-40 mm diam.) and with a mammilate central umbo, rhizomorphs are absent, basidiospores are amygdaliform to ellipsoid and larger (6.5-8 x 4-6.5 [mu]m), the pileipellis is a loosely entangled layer of ascending cylindrical hyphae (Baroni, 1981).
2) were measured on the right valve of the shell of each mussel, using electronic callipers or a microscope eyepiece micrometer, to the nearest 0.1 mm: the shell length (L), the distance from the umbo to the posterior boundary of the ligament (l), and the distance from the umbo to the anterior boundary of the prismatic layer under the ligament nympha (a).
They also established that the genes encoding for chitin synthase and PFMG2 were highly expressed at the D-veliger stage, whereas PFMG6, PFMG8, and PfN23 were significantly upregulated at the umbo stage.
Umbo CV : Developing neural network based AI programs with applications in online and offline surveillance.