logic

¹ American  

[loj-ik] / ˈlɒdʒ ɪk /

noun

1. the science that investigates the principles governing correct or reliable inference.

2. a particular method of reasoning or argumentation.

   We were unable to follow his logic.

3. the system or principles of reasoning applicable to any branch of knowledge or study.

4. reason or sound judgment, as in utterances or actions.

   There wasn't much logic in her move.

   Synonyms:

   cogency, sense

5. convincing forcefulness; inexorable truth or persuasiveness.

   the irresistible logic of the facts.

6. Computers. logic circuit.

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-logic ² American  

1. a combining form used in the formation of adjectives corresponding to nouns ending in -logy:

   analogic.

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logic British  

/ ˈlɒdʒɪk /

noun

1. the branch of philosophy concerned with analysing the patterns of reasoning by which a conclusion is properly drawn from a set of premises, without reference to meaning or context See also formal logic deduction induction

2. any particular formal system in which are defined axioms and rules of inference Compare formal system formal language

3. the system and principles of reasoning used in a specific field of study

4. a particular method of argument or reasoning

5. force or effectiveness in argument or dispute

6. reasoned thought or argument, as distinguished from irrationality

7. the relationship and interdependence of a series of events, facts, etc

8. to use excessively subtle or involved logic or argument

9. electronics computing

   1. the principles underlying the units in a computer system that perform arithmetical and logical operations See also logic circuit

   2. ( as modifier )

      a logic element

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logic Scientific  

/ lŏj′ĭk /

1. The study of the principles of reasoning, especially of the structure of propositions as distinguished from their content and of method and validity in deductive reasoning.

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logic Cultural  

1. The branch of philosophy dealing with the principles of reasoning. Classical logic, as taught in ancient Greece and Rome, systematized rules for deduction. The modern scientific and philosophical logic of deduction has become closely allied to mathematics, especially in showing how the foundations of mathematics lie in logic.

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Usage

What does -logic mean? The combining form -logic is used like a suffix meaning “of or relating to a body of knowledge or writing.” In some rare instances, such as dialogic, -logic means "of or relating to a word or discourse," as in dialogic. It is occasionally used in scientific and technical terms. The form -logic comes from Greek -logikós, meaning “of speech or reason," which is derived from logos, meaning “word” or "discourse." To learn more about logos, you can read our entry on the English word logos here. What are variants of -logic?Though it doesn’t have any variants, the suffix -logic is related to the combining form -logy, which is used to form nouns related to adjectives that end in -logic, as in ecology. Additional related forms include -log and -logue. Want to know more? Read our Words That Use articles on all three forms.

Other Word Forms

• logicless adjective
• nonlogic noun

Etymology

Origin of logic¹

First recorded in 1325–75; Middle English logik, from Latin logica, noun use of neuter plural (in Medieval Latin taken as feminine singular) of Greek logikós “of speech or reason”; see origin at logo-, -ic

Origin of -logic²

< Greek -logikós. See logic

Explanation

Some people think of logic as cold in its insistence on reasoning based only on what can be proven. But without logic's systematic thinking, most mathematical and scientific advances would never have been made. Over time, the meaning of logic has expanded to include any system of thought––you might talk about the "three-year-old logic that puts lollipops ahead of safety," or talk about the "flawed logic of thinking that anyone you meet on the Internet must be cool."

Example Sentences

According to reports by Iranian outlets, Ghalibaf addressed the US president, saying that "if you fight, we will fight, if you come forward with logic, we will respond with logic".

From BBC • Apr. 12, 2026

The strategic oil logic illuminates how the war is likely to end, and the options are starker than most commentators acknowledge.

From The Wall Street Journal • Apr. 12, 2026

The same logic applies to animation merchandise and trendy toys.

From Barron's • Apr. 11, 2026

But the movie itself isn’t exactly exploring new frontiers of fear, devolving instead into a familiar slasher-thriller with a climax of strained characterization and confusing spatial logic.

From The Wall Street Journal • Apr. 9, 2026

Its logic was exactly that of the original mortgage bonds.

From "The Big Short" by Michael Lewis

Related Words

• philosophy
• rationale
• sanity
• sense