erosion

Short definition from Wiktionary

Noun

1. 1
   The result of having been worn away or eroded, as by a glacier on rock or the sea on a cliff face.
2. 2
   The changing of a surface by mechanical action, friction, thermal expansion contraction, or impact.
3. 3
   The gradual loss of something as a result of an ongoing process.
4. 4
   Destruction by abrasive action of fluids.
5. 5
   One of two fundamental operations in morphological image processing from which all other morphological operations are derived.
6. 6
   Loss of tooth enamel due to non-bacteriogenic chemical processes.
7. 7
   A shallow ulceration or lesion, usually involving skin or epithelial tissue.
8. 8
   In morphology, a basic operation (denoted ⊖); see Erosion (morphology).