noun

• (uncountable) The result of having been worn away or eroded, as by a glacier on rock or the sea on a cliff face.
• (uncountable) The changing of a surface by mechanical action, friction, thermal expansion contraction, or impact.
• (uncountable, figurative) The gradual loss of something as a result of an ongoing process.
• (uncountable) Destruction by abrasive action of fluids.
• (mathematics, image processing) One of two fundamental operations in morphological image processing from which all other morphological operations are derived.
• (dentistry) Loss of tooth enamel due to non-bacteriogenic chemical processes.
• (medicine) A shallow ulceration or lesion, usually involving skin or epithelial tissue.
• (mathematics) In morphology, a basic operation (denoted ⊖); see Erosion (morphology).