annulus

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annulus

A mushroom's annulus forms a delicate ring around its stem.

Definition
  1. Noun:
    • (Geometry) A ring-shaped object, figure, or area; a toroid. Specifically, a plane figure bounded by two concentric circles.
    • (Biology) A ring-shaped structure in a plant, fungus, or animal body. In mycology, it refers to the remnant of the partial veil on a mushroom stalk.
    • (General) Any object or formation resembling a ring.
Usage Examples
  • Noun:
    • The mathematician calculated the area of the annulus. (The area of the ring-shaped region was calculated.)
    • A distinct annulus was visible near the top of the mushroom's stem. (A ring-like structure was visible.)
    • Saturn's rings form a brilliant annulus around the planet. (They form a ring-shaped band.)
Advanced Usage
  • "Annular" (Adjective): Having the form of a ring.
    • An annular eclipse occurs when the moon covers the sun's center, leaving a "ring of fire" visible.
  • In Engineering: An annulus often refers to the space between two concentric cylinders, such as in a pipe or a wellbore.
    • Fluid flows through the annulus between the drill pipe and the casing.
Variants and Related Words
  • Ring: A more common general term for a circular band.
  • Toroid / Torus: The surface or solid described by a circle rotated about an axis; a doughnut shape.
  • Halo: A circle of light, sometimes used poetically or metaphorically similar to annulus (e.g., a halo of smoke).
Synonyms
  • Ring
  • Circle
  • Band
  • Loop (in some contexts)
Related Phrases / Technical Terms
  • Annular space: The ring-shaped gap between two circular objects.
  • Annular ligament: A ring-shaped ligament in anatomy, e.g., in the wrist or elbow.
Related Idioms or Expressions

While "annulus" itself is a technical term and not typically used in idioms, the concept appears in expressions: - "Ring-shaped": The descriptive phrase often used in place of "annular" in non-technical contexts. - The children sat in a ring-shaped formation.

annulus

A mushroom's annulus forms a delicate ring around its stem.

Noun
  1. (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
  2. a toroidal shape
    • a ring of ships in the harbor
    • a halo of smoke

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