What is "sesquiterpene"

n. (context chemistry English) Any terpene formed from three isoprene units, and having fifteen carbon atoms; includes several plant pigments such as the flavones.

Sesquiterpenes are a class of terpenes that consist of three isoprene units and have the empirical formula CH. Like monoterpenes, sesquiterpenes may be acyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids.

Sesquiterpenes are found naturally in plants and insects, as semiochemicals, e.g. defensive agents or pheromones.