From OE 'frost,' from PIE *preus- (to freeze, to burn with cold) — a root connecting the sensations of freezing and burning.
A deposit of small white ice crystals formed on the ground or other surfaces when the temperature falls below freezing; also, the atmospheric condition causing this.
From Old English frost, forst ("the freezing of water, frozen dew, intense cold"), from Proto-Germanic *frustaz ("frost"), derived from PIE *prews- ("to freeze, burn with cold"). The PIE root shows a characteristic Indo-European polarity where the same root denotes both extreme cold and a burning sensation — compare Latin prūīna ("hoarfrost"), pruriō ("I itch/burn"), and Sanskrit pruṣvá ("frost, frozen drop"). This thermal ambiguity reflects ancient perceptual experience
The PIE root *preus- (to freeze) may be connected to *preus- (to burn), reflecting an ancient insight that extreme cold and extreme heat produce similar sensations — the 'burn' of frostbite. Latin 'pruīna' (hoarfrost) comes from the same root. The poet Robert Frost, whose surname literally means 'ice,' wrote the famous line 'Some say the world will end in fire, / Some say in ice' — unwittingly echoing the etymological unity of burning