A vermicide is a substance that kills parasitic worms living in the intestine — from the Latin vermis, worm, and caedere, to kill. The term covers antiparasitic medicines such as mebendazole and albendazole, which destroy roundworms, hookworms, and whipworms in humans and livestock, and traditional plant remedies with worm-killing properties. In human medicine, mass deworming programmes using vermicides are among the most cost-effective health interventions in tropical regions, improving children’s growth, appetite, and school performance. In agriculture, wormers protect livestock productivity. Resistance is a growing concern in veterinary use, driving careful dosing and rotation of drug classes. The goal is elimination of the parasite without harming the host.