deduce

American  

[dih-doos, -dyoos] / dɪˈdus, -ˈdyus /

verb (used with object)

deduced, deducing

1. to derive as a conclusion from something known or assumed; infer.

   From the evidence the detective deduced that the gardener had done it.

   Synonyms:

   determine, gather, reason, conclude

2. to trace the derivation of; trace the course of.

   to deduce one's lineage.

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deduce British  

/ dɪˈdjuːs /

verb

1. (may take a clause as object) to reach (a conclusion about something) by reasoning; conclude (that); infer

2. archaic to trace the origin, course, or derivation of

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Other Word Forms

• deducibility
  noun
• deducible
  adjective
• deducibleness
  noun
• deducibly
  adverb
• nondeducible
  adjective
• subdeducible
  adjective
• undeduced
  adjective
• undeducible
  adjective

Etymology

Origin of deduce

First recorded in 1520–30; from Latin dēdūcere “to lead down, derive,” from dē- de- + dūcere “to lead”

Explanation

To deduce is to figure something out based on what you already know. When you see a person crying, it's easy to deduce that the person is sad. Unless they're happy, of course. Sometimes happy people cry. Derived from the Latin ducere, meaning "to lead," a person who deduces something is "leading" their mind from one idea to the next. Deduction is a noun from the verb deduce: it's what we call something that we learn when we deduce. Sherlock Holmes, the famous investigator created by Arthur Conan Doyle, was a master of deduction. He could deduce from a few small clues all of the facts of a murder case.

Example Sentences

The WHO was trying to deduce how hantavirus had appeared on the ship, with the first person who died having developed symptoms on April 6.

From Barron's • May 5, 2026

His tales of Sherlock Holmes didn’t always present enough clues for readers—who could hardly be expected to compete with the brilliant detective—to deduce the solution on their own.

From The Wall Street Journal • Feb. 20, 2026

The host was primed, based on his own observations, to deduce that something highly suspicious was going on.

From Slate • Nov. 12, 2025

So what can we deduce from all of this?

From BBC • Oct. 16, 2025

And because nature was the embodiment of reason it was, in principle, possible to deduce how things had to be.

From "The Invention of Science" by David Wootton

Related Words

• deduct
• glean
• infer
• presuppose
• surmise