Sesquipedalian
Sesquipedalian is an English adjective and noun denoting either a long, polysyllabic word or a style characterized by the use of such words. The term derives from Latin sesquipedalis, literally “a foot and a half long,” famously used by the poet Horace in Ars Poetica; modern dictionaries record English use from the 17th century, with the adjective sense attested in 1656.