catnip or catmint, strong-scented perennial herb (Nepeta cataria) of the family Labiatae (mint family), native to Europe and Asia but naturalized in the United States. A tea of the leaves and flowing tops has long been used as a domestic remedy for various ailments. Catnip is best known for its stimulating effect on cats. Catnip is classified in the division Magnoliophyta, class Magnoliopsida, order Lamiales, family Labiatae.