equation

noun

equa·​tion i-ˈkwā-zhən 

also -shən

1

a

: 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

To bring governmental enterprises and payment for them into immediate equation …

—R. G. Tugwell

2

a

: 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

But take his extraordinary profile out of the equation, and Paul’s boxing CV doesn’t quite live up to his own hype – with his record of 12 wins and one defeat being somewhat misleading. —Ben Church, CNN Money, 18 Dec. 2025

Among other achievements, Garwin worked with Fermi to build an analog computer to visualize the solutions to the Schrödinger equation, a key equation in quantum physics that defines the motion of particles. —Adam Harrington, CBS News, 18 Dec. 2025

Honest communication is part of that equation. —Susan Caminiti, CNBC, 16 Dec. 2025

Actor, mother of four, and Blake Brown founder Blake Lively doesn’t have a standard gifting equation (see the Tom Cruise coconut cake). —Margaux Anbouba, Vogue, 15 Dec. 2025

Word History

First Known Use

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

Phrases Containing equation

• characteristic equation
• cubic equation
• differential equation
• Diophantine equation
• enter (into) the equation
• equation of time
• linear equation
• parametric equation
• partial differential equation
• personal equation
• quadratic equation
• Schrödinger equation
• simple equation
• wave equation

Rhymes for equation

• abrasion
• caucasian
• eurasian
• evasion
• invasion
• occasion
• persuasion
• asian
• suasion
• athanasian

Kids Definition

equation

noun

equa·​tion i-ˈkwā-zhən 

also -shən

1

: the act or process of equating : the state of being equated

2

a

: a statement of the equality of two mathematical expressions

b

: an expression involving chemical symbols for a chemical reaction

Medical Definition

equation

noun

equa·​tion

i-ˈkwā-zhən also -shən

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