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supercool

[soo-per-kool]
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verb (used with object)

to cool (a liquid) below its freezing point without producing solidification or crystallization; undercool.

verb (used without object)

to become supercooled.

adjective

very cool in temperature, especially of the maximum coolness possible: used as a setting on air conditioners.
Slang. very cool; very sophisticated, up-to-date, unemotional, etc.

Origin of supercool

First recorded in 1905–10; super- + cool
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for supercooling

supercool

verb

chem to cool or be cooled without freezing or crystallization to a temperature below that at which freezing or crystallization should occur. Supercooled liquids are not in equilibrium
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
supercooling in Science

supercool

[sōō′pər-kōōl′]

To cool a substance below a phase-transition temperature without the transition occurring. For example, water can be cooled well below the freezing point without freezing (as often happens in the upper atmosphere); the introduction of an impurity or surface can then trigger freezing. Supercooling is an example of hysteresis. Compare superheat.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.