(ˈ)naf]|thalik-, ÷ (ˈ)nap] noun
Etymology: International Scientific Vocabulary naphthal ine + -ic + acid; probably originally formed as French acide naphtalique
1. : a crystalline acid C 10 H 6 (COOH) 2 formed by oxidation of acenaphthene; 1,8-naphthalene-dicarboxylic acid
2. obsolete : phthalic acid