Pneumonoultramicroscopicsilicovolcanosconiosis: Allegedly, "a lung disease caused by the inhalation of very fine silicate or quartz dust." The word was invented by compounding pneumo-(lung) + ultramicroscopic + silicon + volcano + coniosis, from the Greek konis (dust). In fact, pneumonoultramicroscopicsilicovolcanosconiosis means nothing. It is a factitious and fictitious word that was created as a spoof of the many long run-on terms found in medicine.

Pneumonoultramicroscopicsilicovolcanosconiosis is the epitome of the sesquipedalian words with which medicine is, unfortunately, rife. See also: Sesquipedalian.