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Definition of umbo in English: umbonounPlural umbos, Plural umbones ˈʌmbəʊˈəmboʊ 1historical The central boss of a shield. Example sentencesExamples - The nearly spherical cones have eight to 10 scales, each looking like a shield with a central projection (called an umbo, if you want to impress your botanist or Scrabble-playing friends).
2Biology A rounded knob or protuberance. Synonyms lump, bump, protuberance, projection, protrusion, bulge, swelling, knot, node, nodule, gnarl, growth, outgrowth, excrescence, carbuncle, tumour - 2.1Zoology The highest point of each valve of a bivalve shell.
Example sentencesExamples - Below the umbones, the shell margin is folded inward forming a deep lunula and gaping between both valves.
- In contrast, a strongly obtuse apical angle is associated with an incurved ventral beak that is appressed to the dorsal umbo, resulting in the delthyrium being partly obscured.
- The new species is characterized by a transversely extended, strongly biconvex to globular shell with prominent umbones, relatively numerous costae and a notothyrial cavity supported dorsally by a short median ridge.
- Argonauta attaches the egg-mass to the umbo of the shell near the dorsal arms, not in the mantle cavity or posterior parts of the shell.
- The oldest part of the shell, the umbo, can be recognized as a large hump on the anterior end of the dorsal side of each shell.
- 2.2Botany A central swelling on the cap of a mushroom or toadstool.
Derivatives adjective ʌmˈbəʊnlˌəmˈboʊnl Zoology Relating to or of the nature of an umbo or rounded protruberance. the species lacks a prominent umbonal ridge Example sentencesExamples - Hinge articulation either limited to overlapping shell margins on dorsal side of byssal invagination or consisting of a transposable tooth and socket developed on the umbonal septum.
- Cyzicus having elongate valves; umbo convex; dorsal margin straight; posterior margin slightly flared; growth bands widely spaced in umbonal region, more closely spaced elsewhere.
- The umbonal angle narrows while the shape remains mytiliform and the ‘lunule’ (byssal invagination) remains shallow.
adjective ˈʌmbəneɪtˈʌmbənət Botany Having a rounded knob or protuberance. the figures show an umbonate form Example sentencesExamples - M. oreades has a white spore print, adnate, adnexed or even free gills usually white to pale tan in colour, a mid-sized bell-shaped cap but can later become umbonate as it ages.
- An umbonate colony is elevated more in the center of the colony than the rise across the surface of the colony.
- Other decorative British products of this period include ‘umbonate’ disc brooches.
Origin Early 18th century: from Latin, 'shield boss'. Rhymes Colombo, dumbo, gumbo, jumbo, mumbo-jumbo Definition of umbo in US English: umbonounˈəmboʊˈəmbō 1historical The central boss of a shield. Example sentencesExamples - The nearly spherical cones have eight to 10 scales, each looking like a shield with a central projection (called an umbo, if you want to impress your botanist or Scrabble-playing friends).
2Biology A rounded knob or protuberance. Synonyms lump, bump, protuberance, projection, protrusion, bulge, swelling, knot, node, nodule, gnarl, growth, outgrowth, excrescence, carbuncle, tumour - 2.1Zoology The highest point of each valve of a bivalve shell.
Example sentencesExamples - The oldest part of the shell, the umbo, can be recognized as a large hump on the anterior end of the dorsal side of each shell.
- Below the umbones, the shell margin is folded inward forming a deep lunula and gaping between both valves.
- In contrast, a strongly obtuse apical angle is associated with an incurved ventral beak that is appressed to the dorsal umbo, resulting in the delthyrium being partly obscured.
- The new species is characterized by a transversely extended, strongly biconvex to globular shell with prominent umbones, relatively numerous costae and a notothyrial cavity supported dorsally by a short median ridge.
- Argonauta attaches the egg-mass to the umbo of the shell near the dorsal arms, not in the mantle cavity or posterior parts of the shell.
- 2.2Botany A central swelling on the cap of a mushroom or toadstool.
Origin Early 18th century: from Latin, ‘shield boss’. |