- A perennial flowering plant (of the genus Crocus in the Iridaceae family). Saffron is obtained from the stamens of Crocus sativus.
- Any of various similar flowering plants, such as the autumn crocus and prairie crocus.
- (chemistry, obsolete) A deep yellow powder, the oxide of some metal (especially iron), calcined to a red or deep yellow colour.
Most often, the masculine crocus was used to refer to the plant, while the neuter crocum was used for saffron gathered from the plant. However, this distinction is not universally observed, and the word crocus may refer either to the crocus plant or to saffron taken from the plant.