To remove soluble or other constituents from by the action of a percolating liquid: heavy rains that leached the soil of minerals. To remove from a substance by the action of a percolating liquid: acids in groundwater that leach calcium out of the bedrock. To empty; drain:"a world leached of pleasure, voided of meaning"(Marilynne Robinson). 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.