. "Date: 1400-1500 Language: French Origin: Latin laesio, from laedere 'to injure' lesion noun le???sion [countable] technicalMI damage to someone's skin or part of their body such as their stomach or brain, caused by injury or illness: acute gastric lesions Definition of lesion from the Longman Dictionary of Contemporary English within the topic ILLNESS AND DISABILITY" . . . .