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单词 umbo
释义

Definition of umbo in English:

umbo

nounPlural 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
    1. 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. 2.2Botany A central swelling on the cap of a mushroom or toadstool.

Derivatives

  • umbonal

  • 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.
  • umbonate

  • 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:

umbo

nounˈəmboʊˈəmbō
  • 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
    1. 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. 2.2Botany A central swelling on the cap of a mushroom or toadstool.

Origin

Early 18th century: from Latin, ‘shield boss’.

 
 
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更新时间:2024/12/24 9:17:34