ophicleide.
1. Obsolete keyed brass instr. of conical bore and played with cup mouthpiece. Was a development of the serpent and existed in alto, bass, and double-bass sizes, but only the bass was much used. Was used in military bands and is also incl. in early scores of Mendelssohn, Berlioz, Verdi, and Wagner. Superseded by the bass tuba.

2. org. stop like tuba.

ophicleide musical wind-instrument developed from the ancient ‘serpent’. XIX. — F. ophicléïde, f. Gr. óphis serpent (see next) + kleís, kleid- key, rel. to L. clāvis (see CLEF).