Ionone

noun

1. A colorless to yellowish liquid ketone, C13H20O, having the odor of cedar or violets, occurring in either of two isomeric forms, and used chiefly in perfumes.
2. In chem., a hydro-aromatic ketone, made artificially from the citral of lemon-grass and other oils, possessing in a marked degree the odor of violet flowers, and hence used with advantage in modern perfumery.
3. Any of a series of closely related aromatic chemical substances that are part of a group of compounds known as rose ketones, including damascones and damascenones, found in a variety of essential oils.