equa·​tion | \i-ˈkwā-zhən also -shən \

Definition of equation 

1a : the act or process of equating

b(1) : an element affecting a process : factor

(2) : a complex of variable factors

c : a state of being equated specifically : a state of close association or identification bring governmental enterprises and payment for them into immediate equation — R. G. Tugwell

2a : a usually formal statement of the equality or equivalence of mathematical or logical expressions

b : an expression representing a chemical reaction quantitatively by means of chemical symbols

Examples of equation in a Sentence

the equation of material wealth with happiness

Recent Examples on the Web

That is the subject of the title essay, a beautiful story about the friendship between Albert Einstein and the great logician Kurt Gödel, and the moment when the latter man told the celebrated physicist that his equations allowed time travel. Steven Poole, WSJ, "What to Give: Science Books," 15 Nov. 2018 The math works out because, as Albert Einstein taught us with his most famous equation E=mc2 , mass and energy are essentially different expressions of the same thing. Brian Resnick, Vox, "The world is about to redefine the kilogram," 15 Nov. 2018 But there are some quirks and surprises about the math equations that likely will soon vault someone into stratospheric wealth after the jackpots grew for months without a winner. Scott Mcfetridge, The Seattle Times, "Mega Millions, Powerball prizes come down to math, long odds," 23 Oct. 2018 But legal experts say that the effort to remove states from the consumer protection equation rests on shaky legal ground, and may only buy the telecom sector time rather than rolling back the law completely. Recode Staff, Recode, "Recode Daily: Did Chinese spies infiltrate Apple and Amazon with tiny chips?," 4 Oct. 2018 The question is how much, how long, and what impact AMD will have on the equation. Mark Hachman, PCWorld, "Intel supply woes could lead to pricier PCs, or a stampede to AMD's Ryzen," 28 Sep. 2018 The whole first act is a flurry of Spacek and Strathairn sketching out equations, manhandling notebooks, and shooting each other looks that say more than most dialogue usually does. Sean O'kane, The Verge, "LCD Soundsystem’s new music video is basically a Rian Johnson short film," 27 Sep. 2018 Moreover, the equation of salt water plus sun that rounds out most vacation checklists has truly mythic effects on hair. Mackenzie Wagoner, Glamour, "7 Pro Surfers on the Best Deep Conditioners," 17 Sep. 2018 This equation has produced a seller’s market, where prospective buyers are all bidding on the same few houses, driving up prices. Jeff Andrews, Curbed, "Is the housing market starting to cool off?," 2 Aug. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'equation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of equation

14th century, in the meaning defined at sense 1a

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Last Updated

27 Nov 2018

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The first known use of equation was in the 14th century

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English Language Learners Definition of equation

mathematics : a statement that two expressions are equal (such as 8 + 3 = 11 or 2x – 3 = 7)

: a complicated situation or issue

: the act of regarding two things as the same : the act of equating things


equa·​tion | \i-ˈkwā-zhən \

Kids Definition of equation

1 : a statement of the equality of two mathematical expressions

2 : an expression representing a chemical reaction by means of chemical symbols


equa·​tion | \i-ˈkwā-zhən also -shən\

Medical Definition of equation 

: an expression representing a chemical reaction quantitatively by means of chemical symbols

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More from Merriam-Webster on equation

Rhyming Dictionary: Words that rhyme with equation

Spanish Central: Translation of equation

Nglish: Translation of equation for Spanish Speakers

Britannica English: Translation of equation for Arabic Speakers

Britannica.com: Encyclopedia article about equation

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