1. The boss or protuberant part of a shield; the point of a bivalve shell immediately above the hinge.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• umble,
• ombo,
• umo,
• ymbo,
• hmbo,
• 8mbo,
• 7mbo,
• unbo,
• ukbo,
• ujbo,
• umvo,
• umno,
• umho,
• umgo,
• umbi,
• umbk,
• umbp,
• umb0,
• umb9,
• uymbo

• ump.

The adjective form of the word "umbo" is "umbral".