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# entropy

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noun en·tro·py \ˈen-trə-pē\

plural

## entropies

1. 1 :  a measure of the unavailable energy in a closed thermodynamic system that is also usually considered to be a measure of the system's disorder, that is a property of the system's state, and that varies directly with any reversible change in heat in the system and inversely with the temperature of the system; broadly :  the degree of disorder or uncertainty in a system

2. 2 a :  the degradation of the matter and energy in the universe to an ultimate state of inert uniformity b :  a process of degradation or running down or a trend to disorder

3. 3

## Did You Know?

With its Greek prefix en-, meaning "within", and the trop- root here meaning "change", entropy basically means "change within (a closed system)". The closed system we usually think of when speaking of entropy (especially if we're not physicists) is the entire universe. But entropy applies to closed systems of any size. Entropy is seen when the ice in a glass of water in a warm room melts—that is, as the temperature of everything in the room evens out. In a slightly different type of entropy, a drop of food coloring in that glass of water soon spreads out evenly. However, when a nonphysicist uses the word, he or she is usually trying to describe a large-scale collapse.

## Origin and Etymology of entropy

International Scientific Vocabulary 2en- + Greek tropē change, literally, turn, from trepein to turn

First Known Use: 1875

## entropy

play
noun en·tro·py \ˈen-trə-pē\

plural

## entropies

1. :  a measure of the unavailable energy in a closed thermodynamic system that is also usually considered to be a measure of the system's disorder and that is a property of the system's state and is related to it in such a manner that a reversible change in heat in the system produces a change in the measure which varies directly with the heat change and inversely with the absolute temperature at which the change takes place; broadly :  the degree of disorder or uncertainty in a system

## Seen and Heard

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#### glaucous

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of a yellow-green or bluish-gray color

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