make viscous or dense; "thicken the sauce by adding flour"
To make a thick, smooth paste by mixing together arrowroot, cornflour or flour, with an equal amount of cold water; stir into the hot liquid and cook, stirring until thickened.
To make a liquid more thick by reducing or adding a roux, starch, or eggs.
To make a liquid thicker (denser), usually by adding flour, cornstarch or beaten egg, then cooking the mixture.
To make a liquid dense by adding flour, cornstarch, egg yolks, rice or potatoes.