fog

¹ American  

[fog, fawg] / fɒg, fɔg /

noun

1. a cloudlike mass or layer of minute water droplets or ice crystals near the surface of the earth, appreciably reducing visibility.

2. 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.

   Synonyms:

   dim, darken, blur, cloud, trance, muddle, haze

   Antonyms:

   clarity

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. Physical Chemistry. a mixture consisting of liquid particles dispersed in a gaseous medium.

---

verb (used with object)

fogged, fogging

1. to cover or envelop with or as if with fog.

   The steam in the room fogged his glasses.

2. to confuse or obscure.

   The debate did little else but fog the issue.

   Synonyms:

   obfuscate, obscure, muddy, confuse, befog, becloud

   Antonyms:

   clarify

3. to bewilder or perplex.

   to fog the mind.

   Synonyms:

   befuddle, daze, mystify, muddle

4. Photography. to produce fog on (a negative or positive).

verb (used without object)

fogged, fogging

1. to become enveloped or obscured with or as if with fog.

   Antonyms:

   clear

2. Photography. (of a negative or positive) to become affected by fog.

fog ² American  

[fog, fawg] / fɒg, fɔg /

noun

U.S. and British Dialect.

1. a second growth of grass, as after mowing.

2. long grass left standing in fields during the winter.

---

fog ¹ British  

/ fɒɡ /

noun

1. 1. a second growth of grass after the first mowing

   2. grass left to grow long in winter

---

fog ² British  

/ 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. photog a blurred or discoloured area on a developed negative, print, or transparency caused by the action of extraneous light, incorrect development, etc

5. a colloid or suspension consisting of liquid particles dispersed in a gas

---

verb

1. to envelop or become enveloped with or as if with fog

2. to confuse or become confused

   to fog an issue

3. photog to produce fog on (a negative, print, or transparency) or (of a negative, print, or transparency) to be affected by fog

fog Scientific  

/ fôg /

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.

---

fog Idioms  

1. see in a fog.

---

Related Words

See cloud.

Other Word Forms

• fogless adjective
• unfogged adjective
• unfogging adjective

Etymology

Origin of fog¹

First recorded in 1535–45; perhaps by back formation from foggy; fog ²

Origin of fog²

First recorded in 1300–50; Middle English fogge, from Scandinavian; compare Norwegian fogg “long, scattered grass on damp ground”; further origin uncertain; foggy

Example Sentences

The fog of war has stoked a massive surge in the market’s so-called “fear gauge,” the Cboe Volatility Index, or VIX, over the past two months, taking it to levels normally associated with extreme volatility.

From Barron's • Apr. 2, 2026

AI detection tools were meant to cut through the fog of the information war.

From Barron's • Apr. 2, 2026

The differing conclusions of the two reports thickened the fog of uncertainty at the court, which has been operating without a chief prosecutor since Khan went on leave in May of last year.

From The Wall Street Journal • Apr. 1, 2026

"The fog of war continues," investment adviser Christopher Dembik of Pictet Asset Management said.

From Barron's • Mar. 31, 2026

Now, as the fog closed in again and she fumbled for the arrows, she pictured the bear climbing the hill towards her.

From "Wolf Brother" by Michelle Paver

Related Words

• cloud
• gloom
• smog
• smoke
• steam
• vapor