naphthoquinone
noun
naph·tho·qui·none
variants:
also naphthaquinone \ ˌnaf-thə-kwin-ˈōn, ˌnap-, -ˈkwin-ˌōn 
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Medical Definition of naphthoquinone
: any of three isomeric yellow to red crystalline compounds C10H6O2 derived from naphthalene
especially
: one that occurs naturally in the form of derivatives (as vitamin K)