Plural of gamba; a family of stringed instruments popular during the Renaissance, held between the legs like a cello.
From Italian gamba (leg), because the instrument is held between the player's legs. The term entered English during the Renaissance when these instruments were popular in European courts.
Viols were called gambas because they're literally named for the body part you use to play them—imagine if we called the piano the 'armpiano' and you'd get the same idea!
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