umbo

[ uhm-boh ]

noun

, plural um·bo·nes [uhm-, boh, -neez], 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.

umbo

/ ˈʌmbənɪt; ʌmˈbɒnɪk; -ˌneɪt; ˈʌmbəʊ; ˈʌmbənəl /

noun

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

Derived Forms

• umbonate, adjective

Word History and Origins

Origin of umbo¹

1715–25; < Latin umbō boss (of a shield), knob, projecting part; akin to umbilīcus ( umbilicus )

Word History and Origins

Origin of umbo¹

C18: from Latin: boss of a shield, projecting piece

Example Sentences

One species (C. discors) is pale green, with radiating lines from umbo to margin.

From Project Gutenberg

The hand was protected by a hollow conical boss or umbo, fixed to the wood by its brim, but projecting considerably.

From Project Gutenberg

It is a light pelagic form, with paper-like plates and angularly bent carina, with a prominent umbo.

From Project Gutenberg

One is in the Spanish-Moorish style and of a convex shape, with iron bordering and umbo, and a lining of yellow brocade.

From Project Gutenberg

The paracentesis knife is inserted boldly through the membrane a little behind and above the umbo.

From Project Gutenberg