n., pl., um·bo·nes (ŭm-bō'nēz), or um·bos.
- The boss or knob at the center of a shield.
- 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.
- Anatomy. A small projection at the center of the outer surface of the eardrum.
[Latin umbō, umbōn-.]
umbonal um'bo·nal (ŭm'bə-nəl, ŭm-bō'nəl) or um·bon'ic (ŭm-bŏn'ĭk) adj.
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
