umbo noun. ['ʌmbǝʊ] Pl. umbones [ʌm'bǝʊni:z], umbos. E18.
[Latin = shield-boss, knob.]
1. The boss of a shield. E18.

2. A rounded or conical projection or knob, esp. in the centre of a rounded natural structure; spec. (a) Zoology the central tip or highest point of a univalve shell, or of each valve of a bivalve shell; (b) Botany a central swelling on the pileus of a fungus above the stipe; (c) Anatomy the central projection of the inner surface of the eardrum, attached to the malleus. M18.

■ umbonal adjective of, pertaining to, or associated with an umbo; of the nature of an umbo: M19.

■ umbonate adjective (chiefly Botany) formed into or having an umbo or knob E19.

[TahlilGaran] English Dictionary ▲