Meaning

noun hairy aromatic perennial herb having whorls of small white purple-spotted flowers in a terminal spike; used in the past as a domestic remedy; strongly attractive to cats

originCompound of cat + nep, nip (“catnip”), from Middle English nep, from Old English nepte, from Proto-West Germanic *nepetā, from Latin nepeta (“catnip”). Compare earlier catmint (“catnip”), from Middle English catt mynte, which very likely existed in Old English (as *cattes minte) as well.

Etymology from Wiktionary, CC BY-SA 3.0