Sook (gender unknown)
(with) definite article: ?air reservoir: flexible (usually of animal skin), ready for the insertion of stocks
From German "Sack" [bag].
Originally made of animal skin (Previously mainly bitch, later calfskin); Nowadays [i.e. mid-20th century; ws] often of rubber (with a cloth or leather cover).
Habenicht, Gottfried: Der Egerländer Dudelsack. In: Jb. f. ostdeutsche Volkskunde 20 (Marburg, 1977), p.209, 210 [dogskin].
ws (linguistics)