lesion
Concise Oxford English Dictionary © 2008 Oxford University Press:
lesion /ˈliːʒ(ə)n/
▶noun chiefly Medicine a region in an organ or tissue which has suffered damage through injury or disease.
– origin ME: via OFr. from L. laesio(n-), from laedere ‘injure’.
'lesion' also found in these Oxford entries:

