What is the longest word you know of?

Pneumono­ultra­micro­scopic­silico­volcano­coniosi. Longest word in the English language. Not one that you find use for often, it refers to a specific medical condition. And of course, there's anti­dis­establishment­arianism. A tad bit more common, that one. :D

Yup, I can. Antidisestablishmentarianism is the longest word in the english language, weighing in at 28 letters. And the definition, according to Dictionary.com is: "–noun opposition to the withdrawal of state support or recognition from an established church, esp. the Anglican Church in 19th-century England."

For some of the longest words see the url at the end. 28 antidisestablishmentarianism = belief which opposes removing the tie between church and state 34 supercalifragilisticexpialidocious = song title from disney movie mary poppins counts as a word since it is in the English Oxford Dictionary 45 pneumonoultramicroscopicsilicovolcanoconiosis = a long disease caused by breathing volcanic dust www.fun-with-words.com/word_longest.html

Antidisestablishmentarianism. 28 letters

the longest word huh? well i don't think this will mean anything to you because it's not in english but here goes: supercalifragilisticexpiralidocis, or one from medicine but again not in english: sternocleidomastoidian

Supercalifragilisticexpialidocious.. its consists of 34 letters.it means beautiful. i learned about this word when i was in grade school when i first saw the movie Mary Poppins. so far its still the longest word i know.