[ hyoo-mid-i-tee or, often, yoo- ]
/ hyuˈmɪd ɪ ti or, often, yu- /
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humid condition; moistness; dampness.
an uncomfortably high amount of relative humidity: It's not the heat, it's the humidity that tires me out.


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Origin of humidity

1350–1400; Middle English humydite<Latin (h)ūmiditās.See humid, -ity
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


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.

Where does humidity come from?

The first records of the word humidity come from the 1300s. It ultimately derives from the Latin verb (h)ūm(ēre), meaning “to be moist.”

Humidity does, indeed, boil down to moistness—it’s the moistness of the air around you. There are other words for this, like mugginess, but humidity is the most formal (and common) one. Humidity is almost always used to refer to the state of moist air that is also hot—it typically wouldn’t be used to refer to air that’s moist and cold (this is more likely to be referred to as dampness).

Meteorologists (weather scientists) measure humidity in a few different ways. You’ve probably heard them use the term relative humidity, which is the ratio of the actual amount of water vapor in the air (at a given temperature) to the maximum amount that the air could hold at that temperature. Relative humidity is expressed as a percentage—the higher the number, the higher the humidity. Tropical rainforests, for example, have a relative humidity of around 80 percent or higher most of the time. Absolute humidity, on the other hand, is the amount of water vapor that is present in a particular volume of air.

People tend to complain about heat and humidity. There’s a reason it’s uncomfortable. We use sweat to cool off, and humidity prevents evaporation, so when it’s humid out, we can’t cool off as well. This is what people mean when they say, “It’s not the heat—it’s the humidity.”

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What are some other forms related to humidity?

What are some synonyms for humidity?

What are some words that share a root or word element with humidity


What are some words that often get used in discussing humidity?

How is humidity used in real life?

Humidity is used by both meteorologists and laypeople. Most people find humidity uncomfortable, and people often complain about it.



Try using humidity!

Is humidity used correctly in the following sentence?

The humidity is making the air so dry.

How to use humidity in a sentence

British Dictionary definitions for humidity

/ (hjuːˈmɪdɪtɪ) /

the state of being humid; dampness
a measure of the amount of moisture in the airSee relative humidity, absolute humidity
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

Scientific definitions for humidity

[ hyōō-mĭdĭ-tē ]

The amount of water vapor in the atmosphere, usually expressed as either absolute humidity or relative humidity.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for humidity


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.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.