If your lips become sore and cracked from the cold winter wind, you can say they're chapped. Little kids tend to lick their chapped lips, which makes them even more chapped.
Skiers, winter hikers, sailors, and others who spend time outdoors in cold or windy conditions are probably familiar with chapped lips. Other exposed parts of your body can get chapped as well. Chapped comes from the verb chap, "become cracked," from the 15th century chappen, "to split or burst open." Beyond this, the roots of chapped aren't certain, though it may be related to the Middle Dutch kappen, "to cut."