To remove soluble or other constituents from by the action of a percolating liquid. To empty; drain: "a world leached of pleasure, voided of meaning\u201d ( Marilynne Robinson). To be dissolved or passed out by a percolating liquid. The act or process of leaching. A porous, perforated, or sievelike vessel that holds material to be leached. The substance through which a liquid is leached.