American Heritage® Dictionary of the English Language, Fourth Edition
- n. The boss or knob at the center of a shield.
- n. Biology A knoblike protuberance arising from a surface, as the prominence near the hinge of a bivalve shell or the projection at the scale tip of a seed-bearing cone.
- n. Anatomy A small projection at the center of the outer surface of the eardrum.
Century Dictionary and Cyclopedia
- n. The boss of a shield, central in the case of a circular shield. The umbo was sometimes hollow, convex toward the outer side and within allowing the hand to pass into the hollow and grasp a transverse bar; this form occurs especially in small round shields (see
buckler); sometimes the umbo terminated in a spike which was a formidable weapon of offense.
- n. A boss or knob. In botany, the knob in the center of the pileus or cap of an agaricoid fungus.
- n. 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.
- n. zoology One of the lateral prominence just above the hinge of a bivalve shell.
- n. mycology A bump or protrusion on the top of the cap.
- n. historical The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.
GNU Webster's 1913
- n. The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.
- n. A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane.
- n. (Zoöl.) One of the lateral prominences just above the hinge of a bivalve shell.
- n. a slight rounded elevation where the malleus attaches to the eardrum
- Borrowed from Latin umbo (Wiktionary)
- Latin umbō, umbōn-; see nobh- in Indo-European roots. (American Heritage® Dictionary of the English Language, Fourth Edition)
“Running upward and slightly forward from the umbo is a reddish-yellow streak produced by the manubrium of the malleus.”
“For example, these bivalve shells, probably arks (Arcidae), each had a hole thru its umbo.”
“For example, these bivalve shells, probably arks Arcidae, each had a hole thru its umbo.”
“The above magnified picture was taken from below the varix; the umbo was towards the top.”
“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.”
“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.””
“It is thin and fragile, convex, and then nearly flat, with a slight mound or umbo, but sometimes none.”
“The edges were obtuse, the caps fleshy, then corky, smooth, the upper ends not regular, oblique in the form of an umbo or little knob, the pellicles or outside layers thin and easily separated.”
“+Cap+ dingy sulphur yellow color, ½ to 4 inches broad, at first round with a slight umbo, at length depressed, rather silky, then smooth and even.”
“They are sometimes bell-shaped and then flattened, often with a mound or umbo.”
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