Wiktionary
rotundone
n. (context organic compound English) A sesquiterpene responsible for a peppery taste in wine.
Wikipedia
Rotundone
Rotundone is a sesquiterpene originally discovered in the tubers of cyperus rotundus. Rotundone is also present in the essential oils of black pepper, marjoram, oregano, rosemary, basil, thyme, and geranium, as well as in some Syrah (Shiraz) wines.