n :  a vesicular lesion that typically occurs in or around the mouth, that initially causes pain, burning, or itching before bursting and crusting over, and that is caused by a herpes simplex virus which remains dormant in the body and may be reactivated by a variety of factors (as stress, fever, or sunburn) - called also fever blister  - compare CANKER SORE  .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.