Definition of leach in English:



  • 1[with adverbial of direction] (with reference to a soluble chemical or mineral) drain away from soil, ash, or similar material by the action of percolating liquid, especially rainwater.

    [with object] ‘the nutrient is quickly leached away’
    [no object] ‘pesticides and fertilizers that leach into rivers’
    • ‘Humus being highly colloidal, has the ability to adsorb and retain for future plant use many of the ions such as calcium, magnesium, potassium, phosphates and ammonia which might be leached from the soil and lost in drainage.’
    • ‘The other attraction of these materials, which were developed in the 1970s, is that they continuously leach fluoride and so can help reduce the incidence of recurrent caries.’
    • ‘In Australia, Mangareva, parts of the U.S. Southwest, and many other locations, most of the nutrients had already been leached out of the soil by rainfall.’
    • ‘In the processes generally known as bioleaching, stress-hardy bacteria, which can get all their nutrient requirements from the air and the minerals to be leached, are typically employed to oxidise ores to a more soluble state.’
    • ‘More recently they have speculated that acid rain robs trees of this vital nutrient by leaching it from the soil and by mobilizing aluminum, which interferes with calcium uptake by roots.’
    • ‘If rainfall or irrigation is excessive, nitrate will be leached below the plant?’
    • ‘The sort of feed may have to change, because the wetter winters will probably result in nutrients being leached out of the soil at a faster rate.’
    • ‘He concluded that the pseudomorphs were derived when rainwater penetrating the near-surface layers leached out the sodium carbonate from the original shortite, leaving behind calcium carbonate.’
    • ‘The small chloride ion can also sometimes work its way past protective coatings and leach out soluble iron chloride salts, exposing new surfaces for attack.’
    • ‘When they looked at the data from their 1995-2001 study and saw how much nitrate was being leached from the soil, they realized just how important it is to manage drainage systems carefully.’
    • ‘Precious metals, such as platinum and gold, which may be present on the PCB, can also be leached and recovered electrochemically and reused.’
    • ‘Polyurethane is a fully reacted polymer in which every molecule bonds with another so it is chemically inert, which keeps it from oxidizing or leaching chemicals, theoretically extending tire life.’
    • ‘Soluble minerals are leached from soils on upper slopes, move down the slope, and are often deposited at the foot of the slope.’
    • ‘The pad is used to store a mound of ore through which chemicals percolate to leach out the gold ore, which is then collected and processed into bullion.’
    • ‘It will stop rain leaching nutrients from the soil over the winter, and as it rots down it will improve the soil's texture and fertility quite naturally.’
    • ‘#6 Polystyrene can leach styrene, a possible human carcinogen that may also interfere with hormones.’
    • ‘The key, once you've cleared a patch of ground, is to get something sown or planted to fill the vacuum: otherwise the winter wet will leach nutrients from the soil, and the weeds will undo your good work in a matter of weeks.’
    • ‘One drawback of organic-based products is the tendency of chemicals to leach from the matrix material, leaving parts of the surface unprotected.’
    • ‘This, combined with nutrients being leached out of the soils by high rainfall, may cause weakness in some plants and nutrient deficiency, particularly in sandy soils.’
    • ‘Brackish and ocean waters may contain large quantities of sodium chloride as well as many other soluble compounds leached from the crust of the earth.’
    drain, filter, percolate, filtrate, discharge, strain, leak, separate
    trickle, dribble, drip, ooze, seep
    osmose, lixiviate
    View synonyms
    1. 1.1[with object]Subject (soil, ash, etc.) to a leaching process.
      ‘ash is readily leached’
      • ‘Millions of people in the Himalayas and Andes suffer from goitre and cretinism as glaciation, heavy rainfall and melting snow regularly leach mountain soils of their iodine content.’
      • ‘Both field evidence and binocular microscope inspection of the sediment from East Avenue Range indicate that the sediment is highly leached.’


Old English leccan ‘to water’, of West Germanic origin. The current sense dates from the mid 19th century.