AskDefine | Define frost

Dictionary Definition



1 ice crystals forming a white deposit (especially on objects outside) [syn: hoar, hoarfrost, rime]
2 weather cold enough to cause freezing [syn: freeze]
3 the formation of frost or ice on a surface [syn: icing]
4 United States poet famous for his lyrical poems on country life in New England (1874-1963) [syn: Robert Frost, Robert Lee Frost]


1 decorate with frosting; "frost a cake" [syn: ice]
2 provide with a rough or speckled surface or appearance; "frost the glass"; "she frosts her hair"
3 cover with frost; "ice crystals frosted the glass"
4 damage by frost; "The icy precipitation frosted the flowers and athey turned brown"

User Contributed Dictionary

see Frost



Old English, noun form of freeze



  1. A cover of minute ice crystals on objects that are exposed to the air. Some of these are tree branches, plant stems, leaves, wires, poles, vehicles, rooftops, or aircraft skin. Frost is the same process by which dew is formed except that the temperature of the frosted object is below freezing. Frost can be light or heavy.
    • 1748. David Hume. Enquiries concerning the human understanding and concerning the principles of moral. London: Oxford University Press, 1973. § 47.
      It is more probable, in almost every country of Europe, that there will be frost sometime in January, than that the weather will continue open throughout that whole month ;
  2. The cold weather that would cause frost as in (1) to form.


cover of minute ice crystals
cold weather that would cause frost
  • Dutch: vorst
  • Finnish: pakkanen
  • German: Frost
  • Portuguese: geada
  • Russian: мороз
  • Slovene: zmrzal


  1. To get covered with frost.
  2. To coat something (eg a cake) with white icing to resemble frost.
  3. To anger or annoy.
    I think the boss's decision frosted him, a bit.


to get covered with frost
  • Finnish: huurtua
to coat with white icing to resemble frost
to anger or annoy



  1. frost

See also





Extensive Definition

Frost is a solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air. Frost crystals' size differ depending on time and water vapor available. Frost is also usually translucent in appearance. There are many types of frost, such as radiation and window frost. Frost causes economic damage when it destroys plants or hanging fruits. It can also damage road surfaces through a process known as frost heaving.


If a solid surface is chilled below the dew point of the surrounding air and the surface itself is colder than freezing, frost will form on the surface. Frost consists of spicules of ice which grow out from the solid surface. The size of the crystals depends on time, temperature, and the amount of water vapor available.
In general, for frost to form the deposition surface must be colder than the surrounding air. For instance frost may be observed around cracks in cold wooden sidewalks when moist air escapes from the ground below. Other objects on which frost tends to form are those with low specific heat or high thermal emissivity, such as blackened metals; hence the accumulation of frost on the heads of rusty nails. The apparently erratic occurrence of frost in adjacent localities is due partly to differences of elevation, the lower areas becoming colder on calm nights. It is also affected by differences in absorptivity and specific heat of the ground which in the absence of wind greatly influences the temperature attained by the superincumbent air.
Because cold air is more dense than warm air, in calm weather cold air pools at ground level. This is known as surface temperature inversion. It explains why frost is more common and extensive in low-lying areas. Areas where frost forms due to cold air trapped against the ground or against a solid barrier such as a wall are known as "frost pockets".
The formation of frost is an example of meteorological deposition.

Types of Frost

Hoar frost

Radiation frost

Radiation frost (also called hoar frost or hoarfrost) refers to the white ice crystals, loosely deposited on the ground or exposed objects, that form on cold clear nights when radiation losses into the open skies cause objects to become colder than the surrounding air. A related effect is flood frost which occurs when air cooled by ground-level radiation losses travels downhill to form pockets of very cold air in depressions, valleys, and hollows. Hoar frost can form in these areas even when the air temperature a few feet above ground is well above freezing. Nonetheless the frost itself will be at or below the freezing temperature of water.
Hoar frost may have different names depending on where it forms. For example, air hoar is a deposit of hoar frost on objects above the surface, such as tree branches, plant stems, wires; surface hoar is formed by fernlike ice crystals directly deposited on snow, ice or already frozen surfaces; crevasse hoar consists in crystals that form in glacial crevasses where water vapour can accumulate under calm weather conditions; depth hoar refers to cup shaped, faceted crystals formed within dry snow, beneath the surface.
Depth hoar is a common cause of avalanches when it forms in air spaces within snow, especially below a snow crust, and subsequent layers of snow fall on top of it. The layer of depth hoar consists of angular crystals that do not bond well to each other or other layers of snow, causing upper layers to slide off under the right conditions, especially when upper layers are well bonded within themselves, as is the case in a slab avalanche.
Hoar frost also occurs around man-made environments such as freezers or industrial cold storage facilities. It occurs in adjacent rooms that are not well insulated against the cold or around entry locations where humidity and moisture will enter and freeze instantly depending on the freezer temperature.

Advection frost

Advection frost (also called wind frost) refers to tiny ice spikes forming when there is a very cold wind blowing over branches of trees, poles and other surfaces. It looks like rimming the edge of flowers and leaves and usually it forms against the direction of the wind. It can occur at any hour of day and night.

Window frost

Window frost (also called fern frost) forms when a glass pane is exposed to very cold air on the outside and moderately moist air on the inside. If the pane is not a good insulator (such as a single pane window), water vapour condenses on the glass forming patterns. The glass surface influences the shape of crystals, so imperfections, scratches or dust can modify the way ice nucleates. If, otherwise, indoor is very humid water would first condense in small droplets and then freeze into clear ice.

Frost flowers

Frost flowers occur when there is a freezing weather condition but the ground is not already frozen. The water contained in the plant stem expands and causes long cracks along. Water, via capillary action, goes out from the cracks and freezes on contact with the air.


Rime is a type of frost that occurs quickly, often under conditions of heavily saturated air and windy conditions. Ships traveling through Arctic seas may accumulate rime on the rigging. Unlike hoar frost, which has a feathery appearance, rime generally has an icy solid appearance. In formation of hoar frost, the water vapor condenses slowly and directly into icy feathers. Rime typically goes through a liquid phase where the surface is wet by condensation before freezing.

Effect on plants

Many plants can be damaged or killed by freezing temperatures or frost. This will vary with the type of plant and tissue exposed to low temperatures.
Tender plants, like tomatoes, die when they are exposed to frost. Hardy plants, like radish, tolerate lower temperatures. Perennials, such as the hosta plant, die after first frosts and regrow when spring arrives. The entire visible plant may completely turn brown until the spring warmth, or will drop all of its leaves and flowers, leaving the stem and stalk only. Evergreen plants, such as pine trees, will withstand frost although all or most growth stops.
Vegetation will not necessarily be damaged when leaf temperatures drop below the freezing point of their cell contents. In the absence of a site nucleating the formation of ice crystals, the leaves remain in a supercooled liquid state, safely reaching temperatures of −4°C to −12°C. However, once frost forms, the leaf cells may be damaged by sharp ice crystals. Certain bacteria, notably Pseudomonas syringae, are particularly effective at triggering frost formation, raising the nucleation temperature to about −2°C. Bacteria lacking ice nucleation-active proteins (ice-minus bacteria) result in greatly reduced frost damage.
The Selective Inverted Sink prevents frost by drawing cold air from the ground and blowing it up through a chimney. It was originally developed to prevent frost damage to citrus fruits in Uruguay.
frost in Arabic: صقيع
frost in Aymara: Juyphi
frost in Catalan: Gelada
frost in Czech: Mráz
frost in Danish: Frost
frost in German: Frost
frost in Modern Greek (1453-): Πάχνη
frost in Spanish: Helada (clima)
frost in Esperanto: Frosto (temperaturo)
frost in French: Gelée blanche
frost in Italian: Brina
frost in Hebrew: קרה
frost in Latin: Pruina
frost in Lithuanian: Šerkšnas
frost in Dutch: Rijp
frost in Japanese: 霜
frost in Polish: Szron
frost in Portuguese: Geada
frost in Quechua: Qasa
frost in Russian: Иней
frost in Simple English: Frost
frost in Slovenian: Slana
frost in Serbian: Мраз
frost in Finnish: Kuura
frost in Swedish: Frost
frost in Thai: น้ำค้างแข็ง
frost in Turkish: Kırağı
frost in Ukrainian: Іній
frost in Samogitian: Šerkšnos
frost in Chinese: 霜

Synonyms, Antonyms and Related Words

Jack Frost, benumb, besnow, bite, bitter weather, black frost, blanch, bleach, bleak weather, bomb, bust, cap, chalk, chill, chilliness, climax, cold snap, cold wave, cold weather, coldness, consummate, coolness, crest, crown, culminate, cut, depth of winter, disaffinity, dull thud, enmity, etiolate, fizzle, flat failure, flop, floperoo, freeze, freezing weather, frost line, frost over, frost smoke, frostbite, go through, grizzle, hail, hard winter, head, hoar, hoarfrost, ice, ice over, ice up, iciness, incompatibility, incompatibleness, inhospitality, inimicality, killing frost, lemon, nip, numb, outtop, overarch, overtop, peak, penetrate, personal conflict, pierce, raw weather, refrigerate, rime, rime frost, sharp frost, silver, sleet, snap, snow, snow in, snow under, strain, subzero weather, surmount, tension, tip, top, top off, total loss, turkey, unamiability, uncordiality, unfriendliness, ungeniality, unsociability, washout, white, white frost, whiten, winter, wintry weather, wintry wind, zero weather
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