What is a white crystalline substance, C6H4(OH)2, of the phenol series, found in various plants; -- so called because first obtained by distillation of gum catechu. Called also catechol, oxyphenol. etc called?

pyrocatechin — A white crystalline substance, C6H4(OH)2, of the phenol series, found in various plants; -- so called because first obtained by distillation of gum catechu. Called also catechol, oxyphenol. etc. (Webster's 1913.)