Occurs only in Jeremiah 6:29, in relation to the casting of metal. Probably they consisted of leather bags similar to those common in Egypt.

Noah Webster's New International Dictionary of the English Language

(n. sing. & pl.) An instrument, utensil, or machine, which, by alternate expansion and contraction, or by rise and fall of the top, draws in air through a valve and expels it through a tube for various purposes, as blowing fires, ventilating mines, or filling the pipes of an organ with wind.