marjoram or sweet marjoram, Old World perennial aromatic herb (Marjorana hortensis) of the family Labiatae (mint family), cultivated in gardens for flavoring. The tops yield origanum oil, once used medicinally but more recently for perfuming soaps. The closely related European pot, or wild, marjoram (Origanum vulgare) has similar uses and is the spice usually sold as oregano, although other species may be called oregano. The generic names Marjorana and Origanum are frequently interchanged. Marjoram is classified in the division Magnoliophyta, class Magnoliopsida, order Lamiales, family Labiatae.