A substance utilized to increase the density and viscosity of liquid-based preparations. This can include ingredients such as egg yolks, cream, or roux, which is a mixture of butter and flour that has been cooked together.
A liaison is a thickening agent, commonly made by blending cornstarch and milk, that is utilized to thicken pureed soups and sauces. Other types of liaisons may involve the use of flour or eggs for the same purpose.