Fog vs Vapor

When to use each in English, with meaning, register, and examples.

Fog

Top 1,000 (very common)

Vapor

Top 2,000 (common) B1 noun

Most common: Fog

	Fog	Vapor
Pronunciation	🇬🇧 //fɒg// 🇺🇸 //fɔg//	🇬🇧 //ˈveɪpə// 🇺🇸 //ˈveɪpər//
Meaning	A thick cloud of tiny water drops in the air that makes things hard to see.	A gas or mist that comes from a liquid.
Example	The fog rolled in quickly, making the road almost invisible.	The vapor from the boiling pot filled the kitchen.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 2,000 (common)
CEFR level	-	B1
Part of speech		noun
Collocations	heavy fog, thick fog, foggy weather, dense fog, coastal fog	water vapor, vapor pressure, vapor trail, vaporization process
Antonyms	-	solid, liquid
Common mistakes	Confused with 'smog', which is polluted fog, Using 'fog' for a light mist instead of a thick cloud, Incorrectly pluralizing 'fog' as 'fogs'	Confusing with 'steam' which is specifically from boiling water., Using 'vapor' for solid substances instead of gases.
Usage notes	Use 'fog' in both literal and metaphorical senses. In formal writing, avoid using 'fog' figuratively unless context allows.	Use 'vapor' in scientific contexts or when discussing weather. Avoid informal settings.

Frequently asked questions: Fog vs Vapor

What's the difference between Fog and Vapor?

Fog: A thick cloud of tiny water drops in the air that makes things hard to see. Vapor: A gas or mist that comes from a liquid.

Which is more common: Fog and Vapor?

Fog is the most common in everyday English.

Can you show an example of each?

Fog: The fog rolled in quickly, making the road almost invisible. Vapor: The vapor from the boiling pot filled the kitchen.

Can I use Fog and Vapor interchangeably?

Not always. Fog and Vapor are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.