thickening
thick.en.ing n 1: the act of making or becoming thick 2: something used to thicken (as flour in a gravy) 3: a thickened part or place
Webster's English Dictionarythick.en.ing n 1: the act of making or becoming thick 2: something used to thicken (as flour in a gravy) 3: a thickened part or place