scopicsilicovolcanoconiosis

(broke it in two so it fits)

some debate because it is rarely used and created mostly as a hoax and say its:

pseudopseudohypoparathyroidism

the longest non technical word is

flocci­nauci­n

ihili­pili­fication

(again so it fits)

oh my favorite one:

Antidisestablishmentarianism

85 letters- Taumatawhakatangihangakoauauotamateapokaiwhenuakitanatahu

45 letters- Pneumonoultramicroscopicsilicovolcanoconiosis

30 letters- Pseudopseudohypoparathyroidism

29 letters- Floccinaucinihilipilification

(:0)=

(……………..sorry, but this IS words & WORDPLAY, is it not?)

coniosis

http://en.wikipedia.org/wiki/Longest_word_in_English

http://members.aol.com/gulfhigh2/words11.html