frosting UK /ˈfɹɒst.ɪŋ/US /ˈfɹɔst.ɪŋ/ noun3 •(US) Icing, a sweet, often creamy and thick, covering for cakes and other baked goods. •A layer of frost. •The theft of a car while it is left unattended, especially when its engine is left running in the winter to defrost the car. formsfrostings