deduction

American  

[dih-duhk-shuhn] / dɪˈdʌk ʃən /

noun

• deductions
  plural

1. the act or process of deducting; subtraction.

2. something that is or may be deducted.

   She took deductions for a home office and other business expenses from her taxes.

3. the act or process of deducing.

4. something that is deduced.

   His astute deduction was worthy of Sherlock Holmes.

5. Logic.

   1. a process of reasoning in which a conclusion follows necessarily from the premises presented, so that the conclusion cannot be false if the premises are true.

   2. a conclusion reached by this process.

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deduction British  

/ dɪˈdʌkʃən /

noun

1. the act or process of deducting or subtracting

2. something, esp a sum of money, that is or may be deducted

3. 1. the process of reasoning typical of mathematics and logic, whose conclusions follow necessarily from their premises

   2. an argument of this type

   3. the conclusion of such an argument

4. logic

   1. a systematic method of deriving conclusions that cannot be false when the premises are true, esp one amenable to formalization and study by the science of logic

   2. an argument of this type Compare induction

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deduction Scientific  

/ dĭ-dŭk′shən /

1. The process of reasoning from the general to the specific, in which a conclusion follows necessarily from the premises.

2. A conclusion reached by this process.

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deduction ¹ Cultural  

1. A process of reasoning that moves from the general to the specific. (Compare induction.)

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deduction ² Cultural  

1. A cost or expense subtracted from revenue, usually for tax purposes.

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Usage

The logical processes known as deduction and induction work in opposite ways. In deduction general principles are applied to specific instances. Thus, using a mathematical formula to figure the volume of air that can be contained in a gymnasium is applying deduction. Similarly, applying a law of physics to predict the outcome of an experiment is reasoning by deduction. By contrast, induction makes generalizations based on a number of specific instances. The observation of hundreds of examples in which a certain chemical kills plants might prompt the inductive conclusion that the chemical is toxic to all plants. Inductive generalizations are often revised as more examples are studied and more facts are known. If certain plants that have not been tested turn out to be unaffected by the chemical, the conclusion about the chemical's toxicity must be revised or restricted. In this way, an inductive generalization is much like a hypothesis.

Other Word Forms

Derived Forms

• nondeduction
  noun
• prededuction
  noun

Inflected Forms

Nouns

• deductions
  plural

Etymology

Origin of deduction

First recorded in 1400–50; late Middle English deduccioun, from Anglo-French, from Latin dēductiōn-, stem of dēductiō “a leading away”; see deduct, -ion

Explanation

If you get a tax deduction it means you get to reduce the amount of your income that is subject to tax. If something's on sale, you might get a percentage deduction from the original price. Deduction means taking away, or an amount taken away. If you're a fan of Sherlock Holmes, you already know that the process of logical deduction helps to solve crimes––you take away the information you do know to deduce the answer to what you don't. In figure skating, every mistake on the ice results in a point deduction––the judges take points away.

Example Sentences

See Examples For:

deduction deductions

The club also had a six-point deduction "set aside" on appeal.

From BBC ● Sep. 10, 2026

As a result, planners typically recommend keeping enough in traditional IRAs to pay such expenses and get a deduction.

From The Wall Street Journal ● Sep. 4, 2026

More than 7.5 million Americans took advantage of this provision this year, claiming an average deduction of $7,000, according to the US Treasury.

From Barron's ● Aug. 29, 2026

Your main priority now should be planning for the surviving spouse who could face fewer standard deduction, narrower tax brackets and even higher Medicare premiums.

From MarketWatch ● Aug. 25, 2026

He snatched his pad from his pocket, jotted down his deduction while waiting for his cousin to catch up.

From "The Last Last-Day-of-Summer" by Lamar Giles

Taxpayers typically prefer to pair those deductions with wages and business profits taxed up to 37% and not with lower-taxed capital gains.

From The Wall Street Journal ● Aug. 31, 2026

Just because Sami’s meet-and-greet expenses didn’t result in deductions on his taxes, Moll said it doesn’t necessarily mean the IRS wouldn’t allow it elsewhere.

From MarketWatch ● Aug. 25, 2026

It’s used to determine eligibility for certain tax deductions and credits, as well as certain government benefits and surcharges, according to Fidelity.

From MarketWatch ● Aug. 22, 2026

The spending represents a combination of payroll deductions for premiums and out-of-pocket charges like deductibles and copays.

From The Wall Street Journal ● Aug. 20, 2026

It took some inspired deductions by the astronomer William Herschel to work out that they were nowhere near planet sized but much smaller.

From "A Short History of Nearly Everything" by Bill Bryson

Related Words

• abatement
• allowance
• credit
• discount
• rebate
• reduction
• tax write-off
• write-off