How to use leach in a sentence. See examples of leach used in a sentence. leach (liːtʃ) vb 1. Even a small amount of rain can leach the toxic material from the soil. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. The chemical eventually leaches away from the soil. In contrast, leech describes either a parasitic worm or a person who takes advantage of others' generosity. When a chemical substance leaches or is leached from a material, especially soil, it is removed…. A flood can leach important nutrients out of a farmer's field. .