Definition of Mastitis

Mastitis: Inflammation of one or more mammary glands within the breast, usually in a lactating woman. Mastitis can be felt as a hard, sore spot within the breast. Mastitis can be caused by an infection in the breast or by a plugged milk duct. Treatment includes resting and applying warm compresses to the affected area, and for those who are lactating, nursing or expressing milk 'frequently.