[ loj-ik ]
/ ˈlɒdʒ ɪk /
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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.
Should you take this quiz on “shall” versus “should”? It should prove to be a quick challenge!
Question 1 of 6
Which form is used to state an obligation or duty someone has?

Origin of logic

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


log·ic·less, adjectivenon·log·ic, noun

Other definitions for logic (2 of 2)


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

Origin of -logic

<Greek -logikós.See logic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use logic in a sentence

British Dictionary definitions for logic

/ (ˈlɒdʒɪk) /


Word Origin for logic

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

Scientific definitions for logic

[ lŏjĭk ]

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for logic


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 Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.