Oph"i*cleide (?), n. [F. ophicléide, fr. Gr. 'o`fis a serpent + &?;, gen. &?;, a key. So named because it was in effect the serpent, an old musical instrument, with keys added.] (Mus.) A large brass wind instrument, formerly used in the orchestra and in military bands, having a loud tone, deep pitch, and a compass of three octaves; -- now generally supplanted by bass and contrabass tubas. Moore (Encyc. of Music).