Crocus /(krō"kŭs)/

Cro·cus

Crocus

n.
  1. A genus of iridaceous plants, with pretty blossoms rising separately from the bulb or corm. Crocus vernus is one of the earliest of spring-blooming flowers; Crocus sativus produces the saffron, and blossoms in the autumn. (Bot.)
  2. A deep yellow powder; the oxide of some metal calcined to a red or deep yellow color; esp., the oxide of iron (Crocus of Mars or colcothar) thus produced from salts of iron, and used as a polishing powder. (Chem.)

Phrases & Compounds
Crocus of Venus
oxide of copper.