The 20 Longest Words in English and What They Mean

English has accumulated some spectacularly long words over its history, borrowing liberally from Latin and Greek while constructing compound technical terms of astonishing length. Here are the most famous long words and what they actually mean.

The Official Longest Word in English

Pneumonoultramicroscopicsilicovolcanoconiosis (45 letters) is officially recognized as the longest word in a major English dictionary. It refers to a lung disease caused by inhaling very fine silicate or quartz dust. The word was constructed in 1935 by the president of the National Puzzlers' League, Everett M. Smith, deliberately to create a long word.

Other Famously Long Words

Floccinaucinihilipilification (29 letters) means the action of estimating something as worthless. It dates to 1741 and is formed from four Latin words meaning trifle, bagatelle, nothing, and hair. Antidisestablishmentarianism (28 letters) refers to the political position opposing the disestablishment of the Church of England.

Long Words That Are Actually Used

Sesquipedalian (14 letters) means given to using long words, and is beautifully self-referential. Incomprehensibilities (21 letters) is one of the longest common words. Uncharacteristically (20 letters) appears in everyday writing. Counterproductiveness (20 letters) is a real working word.

Scrabble Implications

The longest word ever played in Scrabble is SESQUIOXIDIZING (15 letters, using all tiles plus tiles already on the board). For practical Scrabble, knowing -ING, -TION, and -NESS suffixes allows building words onto existing tiles for board-spanning plays.