approximation

American  

[uh-prok-suh-mey-shuhn] / əˌprɒk səˈmeɪ ʃən /

noun

1. a guess or estimate.

   Ninety-three million miles is an approximation of the distance of the earth from the sun.

2. nearness in space, position, degree, or relation; proximity; closeness.

3. Mathematics, Physics. a result that is not necessarily exact, but is within the limits of accuracy required for a given purpose.

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approximation British  

/ əˌprɒksɪˈmeɪʃən /

noun

1. the process or result of making a rough calculation, estimate, or guess

   he based his conclusion on his own approximation of the fuel consumption

2. an imprecise or unreliable record or version

   an approximation of what really happened

3. maths an inexact number, relationship, or theory that is sufficiently accurate for a specific purpose

4. maths

   1. an estimate of the value of some quantity to a desired degree of accuracy

   2. an expression in simpler terms than a given expression which approximates to it

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Other Word Forms

• approximative adjective

Etymology

Origin of approximation

1400–50; late Middle English approximacioun (< Middle French ) < Medieval Latin approximātiōn-, stem of approximātiō. See approximate, -ion

Explanation

An approximation is a rough estimate or guess at something. When you write a budget for the month, you're making an approximation of how much you're going to spend. You can't be certain of the exact amount. Like approximately or proximity, approximation comes from the Latin proximus which means "nearest." An approximation is the nearest estimate you can get without having the precise size or measure of something. It's a ballpark figure. When you set out for work in the morning, the amount of time you give yourself to get there is an approximation. Depending on traffic and weather, you can never know exactly how long the trip will take.

Example Sentences

Choi recognizes this caveat but said he thinks it is valuable to incorporate even a rough approximation of, say, future earnings rather than exclude them from financial planning.

From The Wall Street Journal • Feb. 19, 2026

It serves as a good approximation of labor demand and can provide some signal for the trajectory of monthly payroll growth.

From Barron's • Jan. 6, 2026

Or they occasionally ponder their spending and saving, which gives them a rough approximation of their cash flow without helping them determine if they’re on track.

From MarketWatch • Dec. 24, 2025

Despite this complexity, a close approximation of its motion can be captured with a simple linear equation that uses only the launch speed and angle.

From Science Daily • Dec. 22, 2025

Measuring angles amounted to eyeballing shadows on a compass, which might do for gross approximation but could not yield very accurate results.

From "Circumference" by Nicholas Nicastro