humidity

American  

[hyoo-mid-i-tee, yoo-] / hyuˈmɪd ɪ ti, yu- /

noun

1. humid condition; moistness; dampness.

2. relative humidity.

3. an uncomfortably high amount of relative humidity.

   It's not the heat, it's the humidity that tires me out.

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humidity British  

/ hjuːˈmɪdɪtɪ /

noun

1. the state of being humid; dampness

2. a measure of the amount of moisture in the air See relative humidity absolute humidity

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humidity Scientific  

/ hyo̅o̅-mĭd′ĭ-tē /

1. The amount of water vapor in the atmosphere, usually expressed as either absolute humidity or relative humidity.

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humidity Cultural  

1. The amount of water vapor in the air. Humidity is measured in two ways: (1) Absolute humidity is the percentage of water vapor actually present in the air. (2) Relative humidity is the absolute humidity divided by the amount of water that could be present in the air. Relative humidity indicates the degree of comfort or discomfort one feels from the humidity, because it indicates the amount of perspiration that can evaporate from the skin.

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Usage

What does humidity mean? Humidity is the state of air when it’s full of water vapor. Humidity is the noun form of the adjective humid, which is used to describe moist air—air that’s full of water vapor. Humidity is most commonly used in reference to weather or the general climate of a place, especially when the temperature is hot. Example: The humidity here in summertime is almost unbearable.

Etymology

Origin of humidity

First recorded in 1350–1400; Middle English humydite, from Latin (h)ūmiditās; equivalent to humid + -ity

Compare meaning

How does humidity compare to similar and commonly confused words? Explore the most common comparisons:

• humidity vs. dew point

Explanation

Humidity has to do with how much moisture is in the air. High humidity is a lot of moisture; low humidity is not much at all. Humidity is a word you'll hear if you watch a weather report, and it's also something people love to complain about. When it's hot and there's a lot of humidity, people sweat a lot — it's uncomfortable, sticky, and your hair is likely to frizz. When the humidity gets really high, there's going to be some rain or snow. In some parts of the country, people have a saying about yucky summer weather: "It's not the heat — it's the humidity."

Example Sentences

The wet-bulb temperature—a combination of humidity and air temperature—must be below 28 degrees.

From Slate • Apr. 11, 2026

According to the World Health Organization, climate change -- through increased rainfall, temperatures and humidity -- can in some cases accelerate malaria transmission by enabling mosquitoes to breed faster.

From Barron's • Apr. 8, 2026

"I think the humidity ticks the boxes here as well," Dicker added.

From BBC • Mar. 31, 2026

Served over ice in a short glass and topped with fruit-salad flotsam, the elixir is lightly caffeinated, mildly fruity and as refreshing as stepping out of the Hanoi humidity into full-blast air conditioning.

From The Wall Street Journal • Mar. 17, 2026

His grief hung around us like humidity, seeping into my skin.

From "The Darkest Minds" by Alexandra Bracken

Related Words

• evaporation
• moisture