noun
also naph·tha·quinone |nafthə, ÷|napthə+
Etymology: International Scientific Vocabulary naphth- + quinone
: any of three isomeric yellow to red crystalline compounds C 10 H 6 O 2 derived from naphthalene ; especially : the alpha or 1, 4-compound that occurs naturally in the form of derivatives (as juglone, lawsone, vitamin K)