A dense, powdery thickening agent made from part of the corn kernel finely ground.
Mix with a small amount of liquid into a slurry or paste before adding to a hot dish, or it will lump. Continued cooking or stirring will cause the thickening to thin.
2 T all-purpose flour = 1 tbsp cornstarch
2 T granular tapioca = 1 tbsp cornstarch
1 T Arrowroot flour = 1 tbsp cornstarch