The longest words in the world

pseudopseudohypoparathyroidism

An inherited disorder that closely simulates the symptons but not the consequences of pseudohypoparathyroidism and, thus it has mild or no manifestations of hypoparathyroidism or tetanic convulsions

floccinaucinihilipilification

Rare . the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).

supercalifragilisticexpialidocious

a nonsense word meaning fantastic; also called supercalifragilistic

pneumonoultramicroscopicsilicovolcanoconiosis

an obscure term ostensibly referring to a lung disease caused by silica dust, sometimes cited as one of the longest words in the English language.

antidisestablishmentarianism

opposition to the withdrawal of state support or recognition from an established church, esp. the Anglican Church in 19th-century England.