-ˌpēn noun
( -s )
Etymology: International Scientific Vocabulary terp- (from German terpentin turpentine, from Medieval Latin terbentina ) + -ene — more at turpentine
1.
a. : any of a class of isomeric hydrocarbons C 10 H 16 (as myrcene, limonene, or pinene) that are found in many essential oils especially from conifers, that have also been synthesized in many cases, that are usually classified according to the absence or presence of one or more rings in the molecule, as acyclic, monocyclic, bicyclic, or tricyclic, and that are used chiefly as solvents and as intermediates in organic synthesis : monoterpene
terpenes and sesquiterpenes
b. : any of a large class of hydrocarbons (C 5 H 8 ) n including the monoterpenes and also hemiterpenes, sesquiterpenes, diterpenes, triterpenes, and polyterpenes that are found especially in essential oils, resins, and balsams, that are regarded in general as structurally constituted of branched five-carbon units (as in isoprene and 2-methyl-butane), and that are also classifiable according to the absence or presence of rings in the molecule
2. : any of various compounds derived from terpene hydrocarbons or closely related to them ; especially : a naturally occurring oxygenated derivative (as geraniol, citral, camphor, or abietic acid) — compare terpenoid