De Morgan's laws

[ dih mawr-guhnz lawz ]

/ dɪ ˈmɔr gənz ˈlɔz /

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noun

(used with a plural verb)Logic. two laws, one stating that the denial of the conjunction of a class of propositions is equivalent to the disjunction of the denials of a proposition, and the other stating that the denial of the disjunction of a class of propositions is equivalent to the conjunction of the denials of the propositions.

(used with a singular verb)Mathematics. the theorem of set theory that states that the complement of the union of two sets is equal to the intersection of the complements of the sets and that the complement of the intersection of two sets is equal to the union of the complements of the sets.

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Also De Mor·gan's law

[dih mawr-guhnz law] /dɪ ˈmɔr gənz ˈlɔ/ .

Origin of De Morgan's laws

First recorded in 1915–20; named after A. De Morgan

Words nearby De Morgan's laws

demonstrative pronouns, demonstrator, demonym, demoralize, De Morgan, De Morgan's laws, demos, demoscene, Demosthenes, demote, demothball

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use De Morgan's laws in a sentence

According to Pew, 14 of the 20 countries in the Middle East and North Africa have blasphemy laws.
In Defense of Blasphemy|Michael Tomasky|January 9, 2015|DAILY BEAST
Have a look at this telling research from Pew on blasphemy and apostasy laws around the world.
In Defense of Blasphemy|Michael Tomasky|January 9, 2015|DAILY BEAST
In the last year, her fusion exercise class has attracted a cult following and become de rigueur among the celebrity set.
How Taryn Toomey’s ‘The Class’ Became New York’s Latest Fitness Craze|Lizzie Crocker|January 9, 2015|DAILY BEAST
They tried to continue their getaway but had to quickly abandon their vehicle on the Rue de Meaux in the 19th.
Police Hunt for Paris Massacre Suspects|Tracy McNicoll, Christopher Dickey|January 7, 2015|DAILY BEAST

Humans spent a long time domesticating cattle, and what they were trying to do, in essence, was de-domesticate them.
‘Nazi Cows’ Tried to Kill British Farmer|Tom Sykes|January 6, 2015|DAILY BEAST
Madame de Condillac stood watching him, her face composed, her glance cold.
St. Martin's Summer|Rafael Sabatini
Then the door opened, the portiere was swept aside, and Anselme announced "Monsieur de Garnache."
St. Martin's Summer|Rafael Sabatini
San Antonio de Bexar lies in a fertile and well-irrigated valley, stretching westward from the river Salado.
Blackwood's Edinburgh Magazine, No. CCCXXXIX. January, 1844. Vol. LV.|Various
“But the laws of Poloeland and those of Flatland are different,” said Amalatok, starting another objection.
The Giant of the North|R.M. Ballantyne
One evening, while he was thus engaged, he observed de Patinos and Duke Wharton enter together.
The Pastor's Fire-side Vol. 3 of 4|Jane Porter

British Dictionary definitions for De Morgan's laws

De Morgan's laws

pl n

(in formal logic and set theory) the principles that conjunction and disjunction, or union and intersection, are dual. Thus the negation of P & Q is equivalent to not-P or not-Q

Word Origin for De Morgan's laws

named after Augustus De Morgan (1806–71), British mathematician

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