log·​ic | \ˈlä-jik \

Definition of logic 

1a(1) : a science that deals with the principles and criteria of validity of inference and demonstration : the science of the formal principles of reasoning a professor of logic

(2) : a branch or variety of logic modal logic Boolean logic

(3) : a branch of semiotics especially : syntactics

(4) : the formal principles of a branch of knowledge the logic of grammar

b(1) : a particular mode of reasoning viewed as valid or faulty She spent a long time explaining the situation, but he failed to see her logic.

(2) : relevance, propriety could not understand the logic of such an action

c : interrelation or sequence of facts or events when seen as inevitable or predictable By the logic of events, anarchy leads to dictatorship.

d : the arrangement of circuit elements (as in a computer) needed for computation also : the circuits themselves

2 : something that forces a decision apart from or in opposition to reason the logic of war

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Other Words from logic

logician \ lō-​ˈji-​shən \ noun

How are logistics and logic related?

Logistics follows the same pattern of other plural nouns—such as ballistics, linguistics, statistics, or physics—that represent fields of study and take either a singular or plural verb.

Logic, used strictly in the singular, is a science that deals with the formal principles of reason. If a visitor walks in the house with wet hair, it is logical for one to assume that it is raining outside. Logistics, which involves such concerns as the delivery of personnel or supplies in an efficient manner, can often employ logic, such as by reasoning out the path least likely to interrupt the flow of a delivery:

As with many other areas of the economy, the digital revolution is having a profound effect on delivery logistics. The combination of mobile computing, analytics, and cloud services, all of which are fueled by the Internet of Things (IoT), is changing how delivery and fulfillment companies are conducting their operations.
—Andrew Meola, Business Insider, 14 Oct. 2016

Both logic and logistics ultimately derive from the Greek logos, meaning "reason." But while logic derives directly from Greek, logistics took a longer route, first passing into French as logistique, meaning "art of calculating," and then into English from there.

Examples of logic in a Sentence

If you just use a little logic, you'll see I'm right. There's no logic in your reasoning. There's some logic to what he says. There's a certain logic in what he says. The revolution proceeded according to its own logic. the logic of the situation
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Recent Examples on the Web

The cast — which also memorably includes Denis Conway as Padraic’s dad and Chris Walley as the young idiot next door — effortlessly conveys the illogical logic and perverse mundanity of the dialogue. Ben Brantley, New York Times, "Orlando Bloom and Aidan Turner Are Drenched in Blood in London," 4 July 2018 In partnership with kids-friendly computer system Tynker, Mattel will also offer six free coding lessons that focus on problem-solving, logic and other coding skills. Niki Mcgloster, Essence.com, "The Quick Read: Kenya Moore Shows Off Her Growing Baby Bump On Instagram," 2 July 2018 To require the [Office of Attorney General] to ignore such evidence of potential criminal activity runs counter to logic and would potentially permit criminal activity to go uninvestigated and unpunished. Peter Smith, Philly.com, "Two Pa. dioceses tried to block grand jury probe into clergy sex abuse, documents show," 29 June 2018 There's a whole hell of a lot of things wrong with the statement, the logic and that Trump decided to voice it. Chris Cillizza, CNN, "4 takeaways on Donald Trump's absolutely appalling statement on the Eagles' White House visit," 4 June 2018 Use logic and personal advice to help your child learn to distinguish between fantasy and reality. Rachel Spector, Msw, miamiherald, "Here's how to chase away your child's scary dreams | Miami Herald," 25 May 2018 But both logic and the law of averages suggest that kind of dominance can't go on forever. Ken Goe, OregonLive.com, "Ducks to keep next week's Pac-12s in mind at Oregon Twilight: Oregon track & field rundown," 3 May 2018 Reason and logic tells us this cannot be possible . . . Bess Levin, The Hive, "Trump’s Pee-Tape Alibi Is Falling Apart," 23 Apr. 2018 What if the prevailing mood of our times is a giddy reversal of progress, logic and beauty, and all of it shoved in our faces with news alerts and indignant tweets? Morgan Enos, Billboard, "Superchunk's Video for 'Erasure' Is a Shot of Power Pop for Nerve-Jangled Times: Watch," 23 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'logic.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of logic

12th century, in the meaning defined at sense 1a(1)

History and Etymology for logic

Middle English logik, from Anglo-French, from Latin logica, from Greek logikē, from feminine of logikos of reason, from logos reason — more at legend

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Statistics for logic

Last Updated

8 Nov 2018

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Time Traveler for logic

The first known use of logic was in the 12th century

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More Definitions for logic



English Language Learners Definition of logic

: a proper or reasonable way of thinking about or understanding something

: a particular way of thinking about something

: the science that studies the formal processes used in thinking and reasoning


log·​ic | \ˈlä-jik \

Kids Definition of logic

1 : a proper or reasonable way of thinking about something : sound reasoning There's no logic in what you said.

2 : a science that deals with the rules and processes used in sound thinking and reasoning

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More from Merriam-Webster on logic

Thesaurus: All synonyms and antonyms for logic

Spanish Central: Translation of logic

Nglish: Translation of logic for Spanish Speakers

Britannica English: Translation of logic for Arabic Speakers

Britannica.com: Encyclopedia article about logic

Comments on logic

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playful or foolish behavior

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