Iris (Orris)

Iris in perfumery means orris root — the rhizome of the iris pallida flower, dried for three years and then steam-distilled. The resulting 'orris butter' is one of the most expensive materials in perfumery (upward of $100,000/kg) and smells of powder, butter, and cold cream. It's the note behind 'lipstick' fragrances (Prada Infusion d'Iris, Dior Homme) and the reason those compositions feel 'expensive' and 'cultured' to most noses.