Frosty coating is a term used to describe a thin layer of ice that forms on surfaces when temperatures drop below freezing. HOAR, with four letters, is an old-fashioned word for frost or hoarfrost, which is a white deposit of ice crystals formed by the rapid freezing of water vapor in the air. Icing, with five letters, is a type of frosting made from sugar, butter, and milk or cream, which is often used to decorate cakes and other desserts. RIME, with four letters, is a type of frost that forms when water droplets in fog freeze onto surfaces. All three words are related to the term frosty coating, which is a thin layer of ice that forms on surfaces when temperatures drop below freezing.