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

Offers greater energy density LMR prismatic cells are engineered to disrupt that equation. — Aman Tripathi, Interesting Engineering, 2 Oct. 2026

Pivot Bio puts cotton in the nitrogen equation Pivot Bio is making its case for replacing some of cotton’s synthetic nitrogen fertilizer with crop nutrition technology that delivers nitrogen to plant roots. — Alexandra Harrell, Footwear News, 2 Oct. 2026

When asked who might be the greatest thinker in America, the boy immediately suggests Professor Jacob Barnhardt (Sam Jaffe), an Albert Einstein analogue who's wooed by Klaatu's solutions to a particularly tricksy math equation. — Richard Edwards, Space.com, 2 Oct. 2026

Checking the solution simply requires evaluating the equation with the new values. — Lyndie Chiou, Scientific American, 2 Oct. 2026

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