A Lesion

1. (pathology) A wound or injury.
2. (medicine) An infected or otherwise injured or diseased organ or part, especially such on a patch of skin.
3. (biochemistry) Any compound formed from damage to a nucleic acid.
4. (law) Injury or an unfair imbalance in a commutative contract wherein the consideration is less than half of the market value, which then serves as a basis for the injured party to sue to rescind the agreement.