Noun
The white particles formed by the congelation of dew; white frost.
Source: Webster's dictionaryIn order that the mortar in the joints may not suffer from frosts, drench it with oil-dregs every year before winter begins. Thus treated, it will not let the hoarfrost enter it. Vitruvius
Etymology The Oxford English Dictionary derives the word from two Old English forms: "hoar" ("white," "light-colored," as in "hoarfrost") and "hune" a word of unknown origin designating a class of herbs or plants. Source: Internet
After that, the class met up with Dave Olesen, the owner of Hoarfrost River Huskies Ltd., a northern business that specializes in air charters and dogsled expeditions. Source: Internet
Ideal conditions for hoarfrost to form on snow are cold clear nights, with very light, cold air currents conveying humidity at the right rate for growth of frost crystals. Source: Internet
Klagenfurter Becken in December 2015: on mount Goritschnigkogel there is a distinct inverse hoarfrost margin. Source: Internet