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[fyoo-gey-shuh s] /fyuˈgeɪ ʃəs/
fleeting; transitory:
a sensational story with but a fugacious claim on the public's attention.
Botany. falling or fading early.
1625-35; < Latin fugāci- (stem of fugāx apt to flee, fleet, derivative of fugere to flee + -ous
Related forms
fugaciously, adverb
fugaciousness, fugacity
[fyoo-gas-i-tee] /fyuˈgæs ɪ ti/ (Show IPA),
noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for fugacity
  • The submitter needs to provide the input values used in its fugacity calculations.
  • Furthermore, fugacity modeling predicts minimal distribution to the air phase.
British Dictionary definitions for fugacity


(thermodynamics) Also called escaping tendency. a property of a gas, related to its partial pressure, that expresses its tendency to escape or expand, given by d(logef) = dμ/RT, where μ is the chemical potential, R the gas constant, and T the thermodynamic temperature f
the state or quality of being fugacious


passing quickly away; transitory; fleeting
(botany) lasting for only a short time: fugacious petals
Derived Forms
fugaciously, adverb
fugaciousness, noun
Word Origin
C17: from Latin fugax inclined to flee, swift, from fugere to flee; see fugitive
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for fugacity



"fleeing, likely to flee," 1630s, from Latin fugaci-, stem of fugax "apt to flee, timid," figuratively "transitory, fleeting," from fugere "to flee" (see fugitive) + -ous. Related: Fugaciously; fugaciousness.

Online Etymology Dictionary, © 2010 Douglas Harper
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fugacity in Medicine

fugacity fu·gac·i·ty (fyōō-gās'ĭ-tē)
A measure of the tendency of a substance, often a fluid, to move from one phase to another or from one site to another.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Article for fugacity

a measure of the tendency of a component of a liquid mixture to escape, or vaporize, from the mixture. The composition of the vapour form of the mixture, above the liquid, is not the same as that of the liquid mixture; it is richer in the molecules of that component that has a greater tendency to escape from the liquid phase. The fugacity of a component in a mixture is essentially the pressure that it exerts in the vapour phase when in equilibrium with the liquid mixture.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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