He"li*o*trope (?), n. [F. h'eliotrope, 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.
A plant of the genus Heliotropium; -- called also turnsole and girasole. H. Peruvianum is the commonly cultivated species with fragrant flowers.
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.
See Bloodstone (a).
Heliotrope purple, a grayish purple color.
© Webster 1913.