(ˈ)dī+...- noun
Etymology: International Scientific Vocabulary di- + gallic
1. : a crystalline phenolic ester acid C 14 H 10 O 9 obtained as a decomposition product of tannins or made synthetically and yielding two molecules of gallic acid on hydrolysis — called also meta-digallic acid
2. : gallotannin — used chiefly in pharmacy