Rubigo is a Latin term that means "rust" or "corrosion." There are several synonyms for this term, including oxidation, tarnishing, corrosion, erosion, and decay. The word oxidation specifically refers to the process by which a substance combines with oxygen to form an oxide. Tarnishing, on the other hand, refers to the dulling of a metal over time due to exposure to air and moisture. Corrosion is a general term for the gradual destruction of a material, often through chemical reactions with its surroundings. Erosion is commonly used to refer to the wearing away of a material by mechanical forces, such as wind or water. Finally, decay can refer to the gradual breakdown of organic matter due to natural processes or disease.