Otro (m)
(with) definite article: il: l’air reservoir: flexible (usually of animal skin), ready for the insertion of stocks
From Latin "ǔter" [goatskin / leather bag; wineskin]; Alta Sabina.
Palombini, Giancarlo: Le ciaramelle: la zampogna altosabina. In: La zampogna: gli aerofoni a sacco in Italia (2005), I, p.56.