Frost is a thin, icy coating that forms on very cold, damp nights. During a New England winter, you'll have to scrape frost off your car windshield almost every morning.
Frost is made of tiny crystals of ice that appear white and tend to form on windows, the ground, trees, and cars. While frost can be lovely on a window, with its snowflake shapes and patterns, it can also be dangerous for farm crops if it forms unexpectedly early or late in the year. Frost comes directly from the Old English, and it has a Proto-Germanic root.