Turnsole

Definition:

(a.) A plant of the genus Heliotropium; heliotrope; -- so named because its flowers are supposed to turn toward the sun.
(a.) The sunflower.
(a.) A kind of spurge (Euphorbia Helioscopia).
(a.) The euphorbiaceous plant Chrozophora tinctoria.
(a.) Litmus.
(a.) A purple dye obtained from the plant turnsole. See def. 1 (d).

Compare turnsole with other words:

litmus vs. turnsole