pseudophake \S(Y)U-deh-feyk\ (noun) - A person who has had the natural lenses of his/her eyes replaced with artificial ones.

"I'm sorry to have to say this, but Grandpa has been living the life of a complete pseudophake for five years."

This piece of medical jargon is a back-formation from the adjective "pseudophakic," meaning "pertaining to artificial lenses." In the past, the only treatment for cataracts was to remove the opaque lens, leaving the eye "aphakic" ("without a lens") which subsequently condemned the sufferer to wearing bottle-bottom spectacles. But today the function of the lens can be (partially) restored with a plastic replacement. The condition of being pseudophakic is "pseudophakia." As some small but bizarre compensation, pseudophakia allows us to see ultraviolet light. Our natural lenses are completely opaque to ultraviolet, whereas the replacement lenses let these short wavelengths pass through and stimulate the light receptors at the back of the eye. From the Greek pseudes "false," from pseudein "to lie," combined with phakos, "lentil" because of the similarity in shape between a lens and the seed of the lentil plant. The same story underlies the English word "lens," which is just Latin lens, meaning "lentil," pressed into different service. Our word "lentil" comes from the Latin diminutive lenticula, "small lentil."