Leach/liːtʃ/ Definition 1 of 4Pro Tip 1/3Environmental Context Use 'leach' when discussing environmental issues where substances move with water. Pesticides can leach into groundwater, contaminating it. Pro Tip 2/3Passive Process 'Leach' often implies a process that happens without human action. Nutrients leach away over time in overworked agricultural fields. Pro Tip 3/3Negative Connotation 'Leach' usually suggests a loss of something desirable or necessary. Farmers worry that heavy rains will leach nutrients from their soil.