pneumonoultramicroscopicsilicovolcanoconiosis (n.)

1962, "A facetious word alleged to mean 'a lung disease caused by the inhalation of very fine silica dust' but occurring chiefly as an instance of a very long word" [OED]. Said in an early reference to have been invented by seventh grade students in Norfolk, Virginia.

Alphabetical list

pneumato-

pneumo-

pneumonia

pneumonic

pneumono-

pneumonoultramicroscopicsilicovolcanoconiosis

pneumothorax

Po

*po(i)-

poach

poached