Noun

(uncountable) The act of negating something.

(countable) A denial or contradiction.

* (Thomas Hardy)

But it pleased her to play on my passion / And whet me to pleadings / That won from her mirthful negations / And scornings undue.

(logic, countable) A proposition which is the contradictory of another proposition and which can be obtained from that other proposition by the appropriately placed addition/insertion of the word "not". (Or, in symbolic logic, by prepending that proposition with the symbol for the logical operator "not".)

*

(logic) The logical operation which obtains such (negated) propositions.

* {{quote-web

, date = 2011-07-20 , author = Edwin Mares , title = Propositional Functions , site = The Stanford Encyclopedia of Philosophy , url = http://plato.stanford.edu/archives/fall2011/entries/propositional-function , accessdate = 2012-07-15 }}

Although some of the logicians working in term logic have very complicated treatments of negation, we can see the origin of the modern conception in the extensional tradition as well. In Boole and most of his followers, the negation of a term is understood as the set theoretic complement of the class represented by that term. For this reason, the negation of classical propositional logic is often called ‘Boolean negation’.

Noun

(en noun)

The action of opposing or of being in conflict.

An opposite or contrasting position.

An opponent in some form of competition.

* {{quote-magazine, date=2013-08-10, volume=408, issue=8848, magazine=(The Economist)

, title= Can China clean up fast enough? , passage=That worries the government, which fears that environmental activism could become the foundation for more general political opposition .}}

(astronomy) The apparent relative position of two celestial bodies when one is at an angle of 180 degrees from the other as seen from the Earth.

(senseid)(politics) A political party or movement opposed to the party or government in power.

(legal) In United States intellectual property law, a proceeding in which an interested party seeks to prevent the registration of a trademark or patent.

(chess) A position in which the player on the move must yield with his king allowing his opponent to advance with his own king.