umbo

um·bo  (mb)

n. pl. um·bo·nes (m-bnz) or um·bos

1. The boss or knob at the center of a shield.

2.

a. 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.

b. Anatomy A small projection at the center of the outer surface of the eardrum.

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[Latin umb, umbn-; see nobh- in Indo-European roots.]

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umbo·nal (mb-nl, m-bnl), um·bonic (m-bnk) adj.

Thesaurus

Noun

1.

umbo - 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