periodic acid-Schiff

adjective

-ˈshif 

: relating to, being, or involving a reaction testing for polysaccharides and related substances in which tissue sections are treated with periodic acid and then Schiff's reagent with a reddish violet color indicating a positive test caused by the reaction with Schiff's reagent of aldehydes formed by the oxidation of hydroxyl groups on adjacent carbon atoms or of adjacent hydroxyl and amino groups