The term "sore nipples" refers to discomfort or pain in the breast area, specifically at the point where the nipple meets the areola. This condition can be caused by a variety of factors such as irritation from clothing or bra straps, poor positioning during breastfeeding, or even an allergic reaction to soap or other products that come into contact with the skin. In some cases, sore nipples may also indicate a more serious condition like mastitis or Paget's disease of the breast.