xanthic acidEnglishOxford New American Dictionaryxanthic acid /ˌzanTHik ˈasəd, ˌzænθɪk ˈæsəd / ▸ noun Chemistry an organic acid containing the group —OCS2H, examples of which are typically reactive solids. – ORIGIN early 19th century : xanthic from Greek xanthos ‘yellow’ + -ic.