The Collaborative International Dictionary of English v.0.48:

Corona \Co*ro"na\ (k?-r?"n?), n.; pl. L. Coron[ae] (-n?), E.
   Coronas (-n?z). [L. corona crown. See Crown.]
   1. A crown or garland bestowed among the Romans as a reward
      for distinguished services.
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   2. (Arch.) The projecting part of a Classic cornice, the
      under side of which is cut with a recess or channel so as
      to form a drip. See Illust. of Column.
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   3. (Anat.) The upper surface of some part, as of a tooth or
      the skull; a crown.
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   4. (Zool.) The shelly skeleton of a sea urchin.
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   5. (Astronomy) A peculiar luminous appearance, or aureola,
      which surrounds the sun, and which is seen only when the
      sun is totally eclipsed by the moon.
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   6. (Bot.)
      (a) An inner appendage to a petal or a corolla, often
          forming a special cup, as in the daffodil and jonquil.
      (b) Any crownlike appendage at the top of an organ.
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   7. (Meteorol.)
      (a) A circle, usually colored, seen in peculiar states of
          the atmosphere around and close to a luminous body, as
          the sun or moon.
      (b) A peculiar phase of the aurora borealis, formed by
          the concentration or convergence of luminous beams
          around the point in the heavens indicated by the
          direction of the dipping needle.
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   8. A crown or circlet suspended from the roof or vaulting of
      churches, to hold tapers lighted on solemn occasions. It
      is sometimes formed of double or triple circlets, arranged
      pyramidically. Called also corona lucis. --Fairholt.
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   9. (Mus.) A character [[pause]] called the pause or hold.
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