Citrus.The essential Lime to use for culinary purposes as all parts of the 'Kaffir' are strongly aromatic especially the unusual 'double' leaves - these are a vital ingredient in Thai and Indonesian cuisine. The fruit are green, rough and 'warty' and not particularly juicy. Evergreen.

The word "Kaffir" is Arabic for infidel or what Muslims used to call unbelievers. How it became associated with a Lime tree I have yet to discover. However in this case it has no relation to its use as a derogatory term in some cultures. Citrus Information Pages