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Petrichor: The smell after rainfall


[fog, fawg] /fɒg, fɔg/
a cloudlike mass or layer of minute water droplets or ice crystals near the surface of the earth, appreciably reducing visibility.
Compare ice fog, mist, smog.
any darkened state of the atmosphere, or the diffused substance that causes it.
a state of mental confusion or unawareness; daze; stupor:
The survivors were in a fog for days after the catastrophe.
Photography. a hazy effect on a developed negative or positive, caused by light other than that forming the image, by improper handling during development, or by the use of excessively old film.
Physical Chemistry. a mixture consisting of liquid particles dispersed in a gaseous medium.
verb (used with object), fogged, fogging.
to cover or envelop with or as if with fog:
The steam in the room fogged his glasses.
to confuse or obscure:
The debate did little else but fog the issue.
to bewilder or perplex:
to fog the mind.
Photography. to produce fog on (a negative or positive).
verb (used without object), fogged, fogging.
to become enveloped or obscured with or as if with fog.
Photography. (of a negative or positive) to become affected by fog.
Origin of fog1
1535-45; perhaps by back formation from foggy. See fog2
Related forms
fogless, adjective
unfogged, adjective
unfogging, adjective
3. obfuscation. See cloud. 7. becloud, obfuscate, dim, blur, darken. 8. daze, befuddle, muddle, mystify.
3. clarity. 7. clarify. 10. clear.


[fog, fawg] /fɒg, fɔg/
noun, U.S. and British Dialect.
a second growth of grass, as after mowing.
long grass left standing in fields during the winter.
1300-50; Middle English fogge, fog < Scandinavian; compare Norwegian fogg long grass on damp ground, foggy Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for fog
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British Dictionary definitions for fog


a mass of droplets of condensed water vapour suspended in the air, often greatly reducing visibility, corresponding to a cloud but at a lower level
a cloud of any substance in the atmosphere reducing visibility
a state of mental uncertainty or obscurity
(photog) a blurred or discoloured area on a developed negative, print, or transparency caused by the action of extraneous light, incorrect development, etc
a colloid or suspension consisting of liquid particles dispersed in a gas
verb fogs, fogging, fogged
to envelop or become enveloped with or as if with fog
to confuse or become confused: to fog an issue
(photog) to produce fog on (a negative, print, or transparency) or (of a negative, print, or transparency) to be affected by fog
Word Origin
C16: perhaps back formation from foggy damp, boggy, from fog²


  1. a second growth of grass after the first mowing
  2. grass left to grow long in winter
Word Origin
C14: probably of Scandinavian origin; compare Norwegian fogg rank grass
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for fog

"thick, obscuring mist," 1540s, probably from a Scandinavian source akin to Danish fog "spray, shower, snowdrift," Old Norse fok "snow flurry," fjuk "snow storm." Cf. also Old English fuht, Dutch vocht, German Feucht "moist." Figurative phrase in a fog "at a loss what to do" first recorded c.1600.

"long grass," c.1300, probably of Scandinavian origin, cf. Norwegian fogg "long grass in a moist hollow," Icelandic fuki "rotten sea grass." The connection to fog (n.1), via a notion of long grass growing in moist dells of northern Europe, is tempting but not proven. Watkins suggests derivation from PIE *pu- "to rot, decay."


1590s, from fog (n.1). Related: Fogged; fogging.

Online Etymology Dictionary, © 2010 Douglas Harper
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fog in Science
  1. A dense layer of cloud lying close to the surface of the ground or water and reducing visibility to less than 1 km (0.62 mi). Fog occurs when the air temperature becomes identical, or nearly identical, to the dew point.

  2. An opaque or semiopaque condensation of a substance floating in a region or forming on a surface.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for fog



  1. (also fog it) To run; speed; hurry (1914+ Western)
  2. To throw with great force: Ole Diz was in his prime then, fogging a fastball (1930s+ Baseball)
  3. To attack; shoot •Also recorded as 1920s racketeer talk: I takes me heat an' fogs 'em (1920s+ Western)

Related Terms

in a fog

[origin unknown; probably a substitution for smoke in all senses]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Related Abbreviations for fog


fiber optic gyro
father of the groom
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Idioms and Phrases with fog


see: in a fog
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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