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[loj-ik] /ˈlɒdʒ ɪk/
the science that investigates the principles governing correct or reliable inference.
a particular method of reasoning or argumentation:
We were unable to follow his logic.
the system or principles of reasoning applicable to any branch of knowledge or study.
reason or sound judgment, as in utterances or actions:
There wasn't much logic in her move.
convincing forcefulness; inexorable truth or persuasiveness:
the irresistible logic of the facts.
Computers. logic circuit.
Origin of logic
1325-75; Middle English logik < Latin logica, noun use of neuter plural (in ML taken as feminine singular) of Greek logikós of speech or reason. See logo-, -ic
Related forms
logicless, adjective
nonlogic, noun
4. sense, cogency.


a combining form used in the formation of adjectives corresponding to nouns ending in -logy:
< Greek -logikós. See logic Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for logic


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 (sense 4), induction (sense 4)
any particular formal system in which are defined axioms and rules of inference Compare formal system, formal language
the system and principles of reasoning used in a specific field of study
a particular method of argument or reasoning
force or effectiveness in argument or dispute
reasoned thought or argument, as distinguished from irrationality
the relationship and interdependence of a series of events, facts, etc
chop logic, to use excessively subtle or involved logic or argument
(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
Word Origin
C14: from Old French logique from Medieval Latin logica (neuter plural, treated in Medieval Latin as feminine singular), from Greek logikos concerning speech or reasoning
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for logic

mid-14c., "branch of philosophy that treats of forms of thinking," from Old French logique (13c.), from Latin (ars) logica, from Greek logike (techne) "reasoning (art)," from fem. of logikos "pertaining to speaking or reasoning," from logos "reason, idea, word" (see logos). Meaning "logical argumentation" is from c.1600.

Online Etymology Dictionary, © 2010 Douglas Harper
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logic in Science
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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logic in Culture

logic definition

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.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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