Merriam-Webster Collegiate Dictionary - terpene

 noun  Etymology: International Scientific Vocabulary terp- (from German Terpentin turpentine, from Medieval Latin terbentina) + -ene — more at turpentine  Date: circa 1873 any of various isomeric hydrocarbons C10H16 found present in essential oils (as from conifers) and used especially as solvents and in organic synthesis; broadly any of numerous hydrocarbons (C5H8)n found especially in essential oils, resins, and balsams  • ~less adjective  • terpenoid adjective or noun