fog

UK: /ˈfɒg/ US: /fɑg, fɔg/ ,(fog, fôg)

Inflections of 'fog' (v): (⇒ conjugate)

fogs

v 3rd person singular

fogging

v pres p

fogged

v past

fogged

v past p

WordReference Random House Learner's Dictionary of American English © 2025

fog¹ /fɑg, fɔg/   n., v., fogged, fog•ging. 
n. 

1. Meteorology a cloudlike mass or layer of water droplets near the surface of the earth:
   [uncountable] drove through heavy fog.
2. a state of mental confusion or unawareness:
   [countable* usually singular] lost in a fog, unable to concentrate.

v. 

3. to (cause to) become covered or enveloped with or as if with fog: [~ + object]
   The steam fogged his glasses.
   [no object* (~ + up)]
   The harbor fogged up. The windshield has fogged.
4. to confuse or obscure:
   [~ + object] The debate just fogged the issue.

fog•gy, adj., -gi•er, -gi•est. 

WordReference Random House Unabridged Dictionary of American English © 2025

fog¹  (fog, fôg), n., v., fogged, fog•ging. 
n. 

1. Meteorology a cloudlike mass or layer of minute water droplets or ice crystals near the surface of the earth, appreciably reducing visibility. Cf. ice fog, mist, smog.
2. Meteorology any darkened state of the atmosphere, or the diffused substance that causes it.
3. a state of mental confusion or unawareness;
   daze;
   stupor:
   The survivors were in a fog for days after the catastrophe.
4. 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.
5. Chemistry [Physical Chem.] a mixture consisting of liquid particles dispersed in a gaseous medium.

v.t. 

6. to cover or envelop with or as if with fog:
   The steam in the room fogged his glasses.
7. to confuse or obscure:
   The debate did little else but fog the issue.
8. to bewilder or perplex:
   to fog the mind.
9. Photography to produce fog on (a negative or positive).

v.i. 

10. to become enveloped or obscured with or as if with fog.
11. Photography (of a negative or positive) to become affected by fog.

• perh. by back formation from foggy. See fog² 1535–45

fog′less, adj. 
Synonyms

• 3. obfuscation. See cloud. 
• 7. becloud, obfuscate, dim, blur, darken.
• 8. daze, befuddle, muddle, mystify.

Antonyms

• 3. clarity.
• 7. clarify.
• 10. clear.

fog²  (fog, fôg), n. [U.S. and Brit. Dial.]

1. a second growth of grass, as after mowing.
2. long grass left standing in fields during the winter.

• Scandinavian; compare Norwegian fogg long grass on damp ground, foggy
• Middle English fogge, fog 1300–50

Collins Concise English Dictionary © HarperCollins Publishers::

fog / fɒɡ/ noun

1. 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
2. a cloud of any substance in the atmosphere reducing visibility
3. a state of mental uncertainty or obscurity
4. a blurred or discoloured area on a developed negative, print, or transparency caused by the action of extraneous light, incorrect development, etc

verb (fogs, fogging, fogged)

1. to envelop or become enveloped with or as if with fog
2. to confuse or become confused: to fog an issue
3. to produce fog on (a negative, print, or transparency) or (of a negative, print, or transparency) to be affected by fog

Etymology: 16th Century: perhaps back formation from foggy damp, boggy, from fog²

fog / fɒɡ/ noun

1. a second growth of grass after the first mowing

Etymology: 14th Century: probably of Scandinavian origin; compare Norwegian fogg rank grass