royal icing
hard white icing, made from softly beaten egg whites, icing sugar and sometimes lemon or lime juice
en-GB/ˈɹɔɪəl ˈaɪsɪŋ/
en-US/ˈɹɔɪəl ˈaɪsɪŋ/
hard white icing, made from softly beaten egg whites, icing sugar and sometimes lemon or lime juice