deduction

deduction — noun

1. when you use facts and logic to figure something out and reach a conclusion; als

1.nounB2
Definition

when you use facts and logic to figure something out and reach a conclusion; also, the conclusion that you reach in this way

Example

From the muddy footprints, Detective Romi made a simple deduction about the burglar's path.

make + deduction + about [topic]

Élise's deduction proved correct when the missing keys turned up in the kitchen drawer.

possessive + deduction as conclusion

Common collocations
  • logical deduction
  • make a deduction
  • reach a deduction
  • deduction from the evidence
  • reasonable deduction
  • simple deduction
Synonyms
  • inference

    very similar; inference is slightly broader and can include conclusions drawn from indirect evidence without strict logic

  • reasoning

    focuses more on the thinking process itself rather than the resulting conclusion

  • conclusion

    refers only to the endpoint result, not the logical process that leads there

Grammar Patterns

make + deduction + about [topic]

it + be + deduction + that-clause

deduction + from [evidence]

Usage Note

Often used with 'make' (make a deduction) and 'reach' (reach a deduction). As a process (uncountable), deduction refers to logical reasoning in general: 'scientific deduction'. As a specific result (countable), it names the conclusion itself.

Common Mistakes

I made a deduction that it will rain.' (when meaning a guess).
I made a deduction that the wet ground meant it had rained.
A deduction must be based on known facts and logic, not a random guess.

2. when you take one number or quantity away from another, or the amount removed in

2.nounB1
Definition

when you take one number or quantity away from another, or the amount removed in this way

Example

After the deduction of shipping costs, the final price was still quite reasonable.

deduction of [cost/item]

Rania noticed a small deduction on her grocery receipt that she could not explain.

Common collocations
  • deduction of costs
  • deduction from the total
  • after deduction of expenses
  • ten percent deduction
  • small deduction
Synonyms
  • subtraction

    identical in meaning; subtraction is more common in maths, deduction in financial contexts

  • removal

    broader and less precise; does not imply a numerical calculation

Antonyms

Grammar Patterns

deduction + of [amount/part]

deduction + from [total]

after + deduction + of [costs/expenses]

Usage Note

Countable when referring to a specific subtracted amount (e.g., 'several deductions'). Uncountable when referring to the action of subtracting in general (e.g., 'Deduction of the costs left a small profit').

Common Mistakes

The deduction of the discount meant I loss money.' (wrong word 'loss').
The deduction of the discount meant I saved less than expected.
Use vocabulary about subtraction and saving, not loss, for discounts.

3. money that an employer takes out of your pay before you receive it, usually for

3.nounB1
Definition

money that an employer takes out of your pay before you receive it, usually for things such as tax, health insurance, or retirement savings

Example

Imran checked his payslip and saw a deduction for the new health insurance plan.

deduction for [purpose]

The monthly deduction for pension savings comes straight out of every worker's salary.

Common collocations
  • tax deduction
  • payroll deduction
  • salary deduction
  • deduction for insurance
  • claim a deduction
  • monthly deduction
Synonyms
  • withholding

    more specific; refers to tax taken directly from pay, not other benefit deductions

  • contribution

    different direction — contribution is money you put in; deduction is money taken out

Antonyms
  • refund

    money returned to you, opposite direction of flow

Grammar Patterns

deduction + for [purpose/benefit]

claim + a + deduction + for [expense]

salary/wage + deduction

Usage Note

Countable only — you talk about 'a deduction', 'deductions', 'several deductions'. In tax contexts, 'deduction' also means an expense you can subtract from your taxable income when filing a tax return (e.g., a charitable donation deduction).

Common Mistakes

My tax deduction was low, so I paid a lot of tax.' (vague).
My tax deduction for charitable donations lowered the amount of tax I owed.
Specify what the deduction is for, to avoid ambiguity between payroll deductions and tax-return deductions.

Word family

Synonym discussion

Sense: noun/1

Deduction, inference, reasoning, and conclusion all relate to reaching a belief or idea from available information, but they differ in emphasis. Deduction stresses a logical step-by-step process from known facts to a certain conclusion — it is the most structured of the four. Inference is broader: you can infer something from indirect clues without a strict logical chain, so it allows more guesswork than deduction. Reasoning focuses on the mental activity itself: the way you think through a problem, regardless of whether you reach a definite conclusion. Conclusion is simply the endpoint — the final opinion or result, without describing how you got there. For example: 'Through careful deduction, the detective identified the suspect.' (process + logic). 'From his silence, she made the inference that he was hiding something.' (indirect clue). 'Her reasoning was sound, even though the answer was wrong.' (thinking process). 'They came to the conclusion that the plan would not work.' (endpoint only).

inference ↗reasoning ↗conclusion ↗

Common collocations

Nouns

Adverbs

  • logically

Phrases

  • make a deduction
  • claim a deduction
  • after deduction of

Prepositions

Etymology

LatinFrenchEnglish

Deduction comes from the Latin verb 'deducere', meaning 'to lead down or away' — from 'de-' (down, away) plus 'ducere' (to lead). In Latin, 'deductio' referred to a leading away or withdrawal. The word entered English through French in the 15th century, first used in its literal 'subtraction' sense. By the 1600s, it had also taken on the logical reasoning meaning — following a line of thought down from general principles to a specific conclusion. The payroll sense developed later as an extension of the subtraction meaning, referring to amounts 'led away' from someone's pay before they receive it.