sesquipedalism

adjective Also ses·quip·e·dal [ses-kwip-i-dl] /sɛsˈkwɪp ɪ dl/.

1. given to using long words.
2. (of a word) containing many syllables.

noun

3. a sesquipedalian word.

adjective

1. tending to use very long words
2. (of words or expressions) long and ponderous; polysyllabic

noun

3. a polysyllabic word

n.1610s, “person or thing a foot and a half long,” from Latin sesquipedalia “a foot-and-a-half long,” from sesqui- “half as much again” (see sesqui-) + stem of pes “foot” (see foot (n.)). As an adjective 1650s. Meaning “sesquipedalian word” (1830) is from Latin sesquipedalia verba “words a foot-and-a-half long,” in Horace’s “Ars Poetica” (97), nicely illustrating the thing he is criticizing.