Surface form analyzed as
+ sesquipedalian , from -ism sesqui- ( “ one and a half ” ) + pedalian ( “ of the foot ” ).
Latin sēsquipedālis ( “ a foot and a half long; in metaphorical use, “of an unnatural length, huge, big” ” ), from sēsqui ( “ one and a half times as great ” ) + pedālis ( “ foot ” ). 
( UK ) IPA (: key) /sɛz.kwɪ.pəˈdɛl.i.ən.ɪsm̩/
( US ) IPA (: key) /ˌsɛskwəpəˈdeɪli.ənɪzm̩/
sesquipedalianism ( plural ) sesquipedalianisms
( uncountable ) The practice of using long, sometimes obscure, words in speech or writing.
1995, Michael Cart, From Romance to Realism, , page 257: ISBN 0060242892
His voice here is a marvelous juxtaposition of cool elegance, unaffected hipness, unabashed sesquipedalianism ("the rich bouquet of exuded sebaceousness") and swell conversational slang (...)
( countable ) A very long word.
Related terms Edit
^ From A New and Copious Lexicon of the Latin Language, Compiled Chiefly from the Magnum Totius Latinitatis Lexicon of Facciolati and Forcellini, and the German Works of Scheller and Luenemann , edited by F. P. Leverett, Wilkins, Carter & Co., Boston, 1849.