The buildup of a substance (such as a toxic chemical) in the tissues of a single living organism over its lifetime, because the substance is absorbed faster than it is excreted.

The increasing concentration of a substance at successive trophic levels of a food web. Because energy transfer is only 10% efficient, predators must eat vastly more prey, thus consuming exponentially more concentrated toxins.

Toxins that biomagnify (like DDT, Mercury, PCBs) are lipid-soluble. They get stored in fat tissue and cannot be flushed out via water/urine.