a genus of iridaceous plants, with pretty blossoms rising separately from the bulb or corm. c. vernus is one of the earliest of spring-blooming flowers; c. sativus produces the saffron, and blossoms in the autumn.-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.