A large or low-register variant of the bassoon, deeper and larger than the standard instrument, rare in modern orchestras.
From Italian fagotto + -one (augmentative suffix). Italian augmentative forms create larger or heavier versions of instruments; fagottone literally means 'big fagott.' This variant appeared in baroque and classical periods but fell out of use.
The fagottone was basically the ultra-deep bassoon—imagine trying to get the lowest, grumpiest sounds possible from an already-low instrument, and you've got the idea!
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