Definition of azulene
1a : a liquid hydrocarbon C15H18 of intense blue color found in some essential oils (such as oil of cubebs) and in lignite tar b : any of various blue to violet or green hydrocarbons closely related chemically to this hydrocarbon and occurring naturally in essential oils or formed from various colorless naturally occurring sesquiterpenes
2 : a synthetic blue crystalline unsaturated bicyclic hydrocarbon C10H8 that resembles the isometric naphthalene in some properties but is more active chemically and that is the parent compound of the azulenes; cyclo-penta-cyclo-heptene
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Origin and Etymology of azulene
International Scientific Vocabulary azul- (from Spanish azul blue, from Old Spanish azur, azul) + -ene
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