Patchouli is a bushy herb that grows in tropical parts of Asia. There's a perfume with a dark, musky scent that's made from this plant; this is also called patchouli.
You may be familiar with the scent of patchouli without realizing it — it's often used in incense, essential oil blends, and natural insect repellants, and it's a common ingredient in various perfumes. The patchouli plant, which is cultivated all over Asia, is related to mint, though its smells much stronger, sweet and earthy. The word has Tamil roots, pachchai, "green," and ilai, "leaf."