1. An instrument or machine for showing when the sun arrived at the tropics and equinoctial line.
2. (Science: botany) a plant of the genus Heliotropium; called also turnsole and girasole. H. Peruvianum is the commonly cultivated species with fragrant flowers.
3. An instrument for making signals to an observer at a distance, by means of the suns rays thrown from a mirror.
4. (Science: chemical) see bloodstone . Heliotrope purple, a grayish purple colour.
Origin: f. Heliotrope, L. Heliotropium, gr.; the sun _ to turn, turn. See heliacal, Trope.