Ophicleide

Ophicleide, a keyed brass wind instrument of recent invention, of great compass and power, and of which there are two kinds in use.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Ophelia * Ophir
Ontario, Lake
Ontology
Onyx
Oosterzee, Jan Jakob van
Opal
Open Secret, The
Open, Sesamë
Opera
Opera Bouffe
Ophelia
Ophicleide
Ophir
Ophites
Opie, John
Opinicus
Opitz, Martin von
Oporto
Opportunist
Optimism
Opus Operatum
Oran