The characteristic purplish-red colour of the flowers or leaves of these plants.
A red to purple azo dye used as a biological stain, and in some countries in cosmetics and as a food colouring.
Any of various herbs of the genus Amaranthus.
The seed of these plants, used as a cereal.
A reddish-brown color.
A similar substance based on another metal (usually with qualification, such as "copper rust").
A disease of plants caused by a reddish-brown fungus.
Damage caused to stamps and album pages by a fungal infection.
The deteriorated state of iron or steel as a result of moisture and oxidation.
To (cause to) degenerate in idleness; to make or become dull or impaired by inaction.
To oxidize, especially of iron or steel.
To cause to oxidize.
To be affected with the parasitic fungus called rust.
Of a black cat or its fur, to turn rust-coloured following long periods of exposure to sunlight.