see 3d leech.-a quantity of wood ashes, through which water passes, and thus imbibes the alkali.-a tub or vat for leaching ashes, bark, etc.-to remove the soluble constituents from by subjecting to the action of percolating water or other liquid; as, to leach ashes or coffee.-to dissolve out; -- often used with out; as, to leach out alkali from ashes.-to part with soluble constituents by percolation.-see leech, a physician.