from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Condensed water vapor in cloudlike masses lying close to the ground and limiting visibility.
  • n. An obscuring haze, as of atmospheric dust or smoke.
  • n. A mist or film clouding a surface, as of a window, lens, or mirror.
  • n. A cloud of vaporized liquid, especially a chemical spray used in fighting fires.
  • n. A state of mental vagueness or bewilderment.
  • n. Something that obscures or conceals; a haze: shrouded their actions in a fog of disinformation.
  • n. A blur on a developed photographic image.
  • transitive v. To cover or envelop with or as if with fog.
  • transitive v. To cause to be obscured; cloud.
  • transitive v. To make vague, hazy, or confused: a memory that had been fogged by time.
  • transitive v. To obscure or dim (a photographic image).
  • intransitive v. To be covered with or as if with fog.
  • intransitive v. To be blurred, clouded, or obscured: My glasses fogged in the warm air.
  • intransitive v. To be dimmed or obscured. Used of a photographic image.
  • n. A new growth of grass appearing on a field that has been mowed or grazed.
  • n. Tall, decaying grass left standing after the cutting or grazing season.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A thick cloud that forms near the ground; the obscurity of such a cloud.
  • n. A mist or film clouding a surface.
  • n. A state of mind characterized by lethargy and confusion.
  • n. A silver deposit or other blur on a negative or developed photographic image.
  • v. To become covered with or as if with fog.
  • v. To become obscured in condensation or water.
  • v. To become dim or obscure.
  • v. To cover with or as if with fog.
  • v. To obscure in condensation or water.
  • v. To make confusing or obscure.
  • v. To make dim or obscure.
  • n. A new growth of grass appearing on a field that has been mowed or grazed.
  • n. Tall and decaying grass left standing after the cutting or grazing season.
  • n. Moss.

from the GNU version of the Collaborative International Dictionary of English

  • n. A second growth of grass; aftergrass.
  • n. Dead or decaying grass remaining on land through the winter; -- called also foggage.
  • n. Watery vapor condensed in the lower part of the atmosphere and disturbing its transparency. It differs from cloud only in being near the ground, and from mist in not approaching so nearly to fine rain. See cloud.
  • n. A state of mental confusion.
  • n. Cloudiness or partial opacity of those parts of a developed film or a photograph which should be clear.
  • intransitive v. To practice in a small or mean way; to pettifog.
  • intransitive v. To show indistinctly or become indistinct, as the picture on a negative sometimes does in the process of development.
  • transitive v. To pasture cattle on the fog, or aftergrass, of; to eat off the fog from.
  • transitive v. To envelop, as with fog; to befog; to overcast; to darken; to obscure.
  • transitive v. To render semiopaque or cloudy, as a negative film, by exposure to stray light, too long an exposure to the developer, etc.

from The Century Dictionary and Cyclopedia

  • To envelop with or as with fog; shroud in mist or gloom; obscure; befog.
  • To cloud or coat with a uniform coating or discoloration, as in photography: as, an over-alkaline developer will fog the plate. see fog, n., 3.
  • To become covered or filled with fog.
  • In photography, to become clouded or coated with a uniform coating or discoloration: said of a negative in course of development. See fog, n., 3.
  • To feed off the fog or pasture in winter: as, to fog cattle.
  • To eat off the fog from: as, to fog a field.
  • To become covered with fog or moss.
  • To seek gain by base or servile practices (whence pettifogger).
  • Gross; fat; clumsy.
  • n. The aggregation of a vast number of minute globules of water in the air near the earth's surface, usually produced by the cooling of the air below the dew-point, whereby a portion of its vapor is condensed.
  • n. Hence A state of mental obscurity or confusion: as, to be in a fog of doubt.
  • n. In photography, a uniform coating covering a developed plate, more or less destructive to the picture in proportion to its opacity. It results from chemical impurities, from exposure of the sensitized film to light, from errors in manipulation, etc.
  • n. Aftergrass; a second growth of grass; aftermath; also, long grass that remains on land through the winter; foggage.
  • n. Moss.
  • n. An atmospheric haze due to the presence of fine solid matter, such as dust or fine soot from soft coal fires or ashes from forest and prairie fires. These carbon particles collect about themselves special atmospheres of aqueous vapor and other gases. The spectrum of the transmitted light shows only the red and ultra-red waves. As the upper layers of the dry fog cool off by radiation and the little atmospheres of vapor become water, the dry fog changes to a drizzling mist and often to steady rain. Prairie fires and the resultant dry fog are mentioned by Marco Polo in his travels in India.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • v. make less visible or unclear
  • n. droplets of water vapor suspended in the air near the ground
  • n. confusion characterized by lack of clarity
  • n. an atmosphere in which visibility is reduced because of a cloud of some substance


Perhaps of Scandinavian origin.
Middle English fogge, tall grass; see pū̆- in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Origin uncertain; perhaps a back-formation from foggy. or perhaps related to the Dutch vocht and German feucht (moisture) (Wiktionary)
Origin uncertain; compare Norwegian fogg. (Wiktionary)



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  • "fog" in Hungarian means: take / tooth / shall - and is, therefore, a homograph in its own right already in that language

    August 1, 2012

  • “Dr. Haas collaborated with BlackGold Biofuels, a small Philadelphia company that has developed a process for making biodiesel fuel out of a wide range of nonedible, low-value “fog” — the industry shorthand for fats, oils and grease.”

    The New York Times, Butter Holds the Secret to the Latest Biodiesel Fuel, by Kenneth Chang, August 9, 2010

    August 11, 2010

  • Not nice to drive through (as I did last night), but can be quite pretty.

    December 21, 2007

  • The fog comes
    on little cat feet.

    It sits looking
    over harbor and city
    on silent haunches
    and then moves on.

    October 21, 2007