Yes, there’s really a molecule with this name. Moronic acid is a triterpene that can be extracted from the hemiparasitic mistletoe plant (Phoradendron reichenbachianum), among other species. It is cytotoxic, which is perhaps the origin of the mistletoe legend. A moronic acid derivative has shown activity against some HIV strains.
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.