formaldehydesulfoxylic acid \ ̷ ̷ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷ˌ ̷ ̷ˌ ̷ ̷ˈ ̷ ̷ ̷ ̷-\noun Etymology: International Scientific Vocabulary formaldehyde + sulfoxylic : an unstable acid HOCH2SO2H known only in the form of salts (as sodium formaldehydesulfoxylate) that are strong reducing agents