/lee"zheuhn/ , n.
1. an injury; hurt; wound.
2. Pathol. any localized, abnormal structural change in the body.
3. Plant Pathol. any localized, defined area of diseased tissue, as a spot, canker, blister, or scab.
v.t.
4. to cause a lesion or lesions in.
[ 1425-75; late ME laesion- (s. of laesio ) injury, equiv. to L laes ( us ) (ptp. of laedere to harm, equiv. to laed- verb s. + -tus ptp. suffix, with -dt- > -s- ) + -ion- -ION ]