basset horn n 1: a tenor clarinet; pitched in the key of F below the B-flat clarinet
Corno di bassetto \Cor"no di bas*set"to\ (k?r"n? d? b?s-s?t"t? or b?s-s?t"t?); pl. {Corni di basseto}. [It.] (Mus.) A tenor clarinet; -- called also {basset horn}, and sometimes confounded with the English horn, which is a tenor oboe. [1913 Webster]
Basset horn \Bas"set horn`\ (b[a^]s"s[e^]t h[^o]rn`). [See {Basset}, a.] (Mus.) An instrument blown with a reed, and resembling a clarinet, but of much greater compass, embracing nearly four octaves; The corno di bassetto. [1913 Webster]