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A rounded elevation of the surface of the tympanic membrane.
(invertebrate zoology)
A prominence above the hinge of a bivalve mollusk shell.



the iron central boss of a shield, which protected the warrior’s hand. Under the hemispherical or conical umbo was a crosspiece by which the shield was held. Shields with umbones were widely used in ancient Greece and Rome and in medieval Europe and Rus’.

References in periodicals archive ?
The inner layer of the ligament is a pyramid-shaped structure situated between the valves under the umbo.
Alternatively, in a functionally relevant approach, the main traits of the shape of shell outline may be synthetically characterised by (i) the shell elongation, that is, the ratio of contour length to contour height, (ii) the valve dissymmetry, namely, the degree of dissymmetry of the position of the umbo versus the anterior and posterior extremities of shell, and (iii) the ventral convexity, that is, the degree of prominence of the ventral side of the shell outline, opposite to umbo.
The experiments showed that when the prototype microphone unit was attached to the umbo, it could pick up medium pitches at conversational volumes, but had trouble detecting quieter, low-frequency sounds.
Concha pequena delgada y alargada, umbo mas cercano al borde anterior redondeado, parte anterior ligeramente mas inflada y la posterior algo estrecha termina truncada; charnela presenta en la valva izquierda un gran condroforo proyectado, y el resilio se inserta en el interior del pico de la valva derecha; escultura consiste en finas costillas conmarginales mas desarrolladas en la vertiente posterior, y el crecimiento irregular ha deformado la superficie de la conchilla; el color es blanco translucido y el periostraco parduzco se proyecta mas alla del borde de la conchilla en el extremo posterior.
According to Bonetto (1967), the genus Anodontites consists of a group of species in whose shell shape varies from oval to eliptical, with subsolid valves (in spite of being fragile for the great development of the prismatic nacreous layer), umbos a little prominent and with no sculptures.
5 cm de largo o mas, transversalmente aquillada, de color castano algo brillante; umbo dorsal, tetra o hexagonal, cafe claro algo lustroso, con cuspide protuberante y gruesa frecuentemente curvada hacia afuera, de color castano oscuro, en las escamas medias hasta de 1.
El margen dorsal esta reflejado por debajo del umbo formando un area para la fijacion del musculo aductor, el cual es importante durante el proceso de perforacion.
The umbo represents the precise centre of the macula, the area of retina that results in the highest visual acuity (VA); it has a very high concentration of cones.
Description: Pentagonal shell, smooth, maximum wide slightly anterior mid line, anterior commissure episulcate, median sinus smaller and narrower than the lateral, umbo sub-erect.