Umbo

Chamber's Twientieth Century Dictionary · 1908 · p. 115

um′bō, n. the bo of a shield: a knob: the point of a bivalve shell immediately above the hinge:— pl. Umbō′nes , Um′bos .— adjs. Um′bōnal , protuberant; Um′bōnāte , -d ( bot. ), having a central umbo, bo , or low rounded projection.— n. Umbonā′tion .— adjs. Umbon′ic ; Umbon′ulate . [L.]