hippopotomonstrosesquipedalianism

noun2

1. •
   (humorous) The use of extremely long words.

   • Or is his unflagging sesquipedalianism—which at times verges on hippopotomonstrosesquipedalianism (adj. pertaining to a very, very long word)—achieved without benefit of accessory? — 1992
2. •
   (humorous) An extremely long word.

   • My god only listens to prayers that are grammatically correct and contain hippopotomonstrosesquipedalianisms or, at least, obscuratanisms. — 2000