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

Shell transversely oblong, thick, depressed, within purple; hinge plate thick, truncate, with an obsolete lamellar tooth in each valve; umbones retuse.

From Project Gutenberg

Shell ovate-oblong, thick, convex, anterior obliquely rounded; hinge margin slightly curved and thickened beneath the umbones; inside fulvous, with a reddish margin.

From Project Gutenberg

In some, coloured bands radiate from the umbones, and well bear out the fanciful name of "Sunset shells" bestowed upon them.

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

Brachiopoda, with the pedicle passing out between the umbones, the opening being shared by both valves.

From Project Gutenberg