The Collaborative International Dictionary of English v.0.48:

Heliotrope \He"li*o*trope\, n. [F. h['e]liotrope, L.
   heliotropium, Gr. ?; ? the sun + ? to turn, ? turn. See
   Heliacal, Trope.]
   1. (Anc. Astron.) An instrument or machine for showing when
      the sun arrived at the tropics and equinoctial line.
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   2. (Bot.) A plant of the genus Heliotropium; -- called also
      turnsole and girasole. Heliotropium Peruvianum is
      the commonly cultivated species with fragrant flowers.
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   3. (Geodesy & Signal Service) An instrument for making
      signals to an observer at a distance, by means of the
      sun's rays thrown from a mirror.
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   4. (Min.) See Bloodstone
      (a) .
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   Heliotrope purple, a grayish purple color.
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