Noun
the bassoon that is the largest instrument in the oboe family
Source: WordNetThe F clef notated to sound an octave lower is used for contrabass instruments such as the double bass and contrabassoon. Source: Internet
The standard woodwind section consists of flutes (one doubling piccolo), oboes (one doubling English horn), soprano clarinets (one doubling bass clarinet), and bassoons (one doubling contrabassoon). Source: Internet
If such a bell is not to be used, then a contrabassoon should be employed. Source: Internet