Bergamot oil: An aromatic extract of the rind of the bergamot orange used to flavor Earl Grey tea and in aromatherapy. It causes photosensitivity, due largely to the presence of 5-methoxypsoralen. Drinking very large amounts of Earl Grey tea can block the intestinal absorption of potassium. Found on http://www.medterms.com/script/main/art.asp?articlekey=20522