The Kaffir LIme is a Southeast Asian citrus fruit, Citrus hystrix. The zest of the pear shaped, wrinkled green fruit is used in cooking, as are the unusually formed leaves. The leaves have a unique double shape that looks like two leaves joined end to end. They have a citrus-floral aroma, with a very distinctive flavor.
Kaffir Lime juice is used in traditional Indonesian medicine.
According to my friend and his wife in Thailand, slices of the kafir lime are used as a deodorant in urinals.