Source : Webster's Revised Unabridged Dictionary (1913)

Sesquipedal \Ses*quip"e*dal\, Sesquipedalian
\Ses`qui*pe*da"li*an\, a. [Sesqui- + pedal: cf. F.
   sesquip['e]dal, L. sesquipedalis.]
   Measuring or containing a foot and a half; as, a
   sesquipedalian pygmy; -- sometimes humorously applied to long
   words.

Source : WordNet®

sesquipedalian
     adj 1: given to the overuse of long words; "sesquipedalian
            orators"; "this sesquipedalian way of saying one has
            no money"
     2: (of words) long and ponderous; having many syllables;
        "sesquipedalian technical terms" [syn: {polysyllabic}]
     n : a very long word (a foot and a half long) [syn: {sesquipedalia}]