umbo

 
Pronunciation: /ˈʌmbəʊ/

noun (plural umbones /-ˈbəʊniːz/ or umbos)

  • 1 historical the central boss of a shield.
  • 2 Biology a rounded knob or protuberance.
  • Zoology the highest point of each valve of a bivalve shell.
  • Botany a central swelling on the cap of a mushroom or toadstool.

Derivatives

umbonal

adjective (chiefly Zoology)

umbonate

Pronunciation: /-nət/
adjective (chiefly Botany)

Origin:

early 18th century: from Latin, 'shield boss'