Hoarfrost (noun)
hawr-frost
a covering of minute ice needles, formed from the atmosphere at night upon the ground and exposed objects when they have cooled by radiation below the dew point, and when the dew point is below the freezing point.
First recorded in 1250–1300, hoarfrost is from the Middle English word hor-frost.See hoar, frost
Example sentences
“The jagged hoarfrost coated the tops of the fenceposts.”