The crossword solution for the term 'Hoarfrost Relative' is RIME, a four letter word. RIME is a type of frost that forms when water vapor in the air condenses directly into ice crystals on surfaces such as trees, grass, and other objects. It is also known as hoar frost, white frost, or radiation frost. RIME is different from other types of frost because it forms quickly and is usually composed of tiny ice crystals.