n. The act or process of infiltrating.n. In pathology, a morbid condition of any portion of tissue produced by the accumulation in it of substances introduced from without: distinguished from degeneration, where the substance abnormally present is produced from the tissue itself through faulty metabolism.n. That which infiltrates; a fluid, or matter carried by a fluid, which enters the pores or cavities of a body.n. In geology, the introduction of water into porous or open-textured rock. The term is specially employed in the discussion of ore-deposits to describe the introduction of new minerals in solution.