rel·​a·​tiv·​i·​ty | \ˌre-lə-ˈti-və-tē \
plural relativities

Definition of relativity 

1a : the quality or state of being relative

b : something that is relative

2 : the state of being dependent for existence on or determined in nature, value, or quality by relation to something else

3a : a theory which is based on the two postulates (1) that the speed of light in a vacuum is constant and independent of the source or observer and (2) that the mathematical forms of the laws of physics are invariant in all inertial systems and which leads to the assertion of the equivalence of mass and energy and of change in mass, dimension, and time with increased velocity

called also special relativity, special theory of relativity

b : an extension of the theory to include gravitation and related acceleration phenomena

called also general relativity, general theory of relativity

Examples of relativity in a Sentence

Recent Examples on the Web

But the fallout of the Michelson-Morley experiment led to the idea of the universal speed of light, inspired Einstein’s breakthroughs in relativity, and opened the door to much of modern physics. Meg Neal, Popular Mechanics, "The Eternal Quest for Aether, the Cosmic Stuff That Never Was," 19 Oct. 2018 Some quantum in your equivalence In relativity, mass and energy are two sides of the same coin. Chris Lee, Ars Technica, "Einstein’s equivalence principle updated with a dash of quantum," 14 Aug. 2018 How could this sort of thing come from the pen of a man then in his 40s and already a world-famous physicist (for his 1905 and 1915 theories on relativity)? Maria Puente, USA TODAY, "Einstein was a racist? His 1920s travel diaries contain shocking slurs against Chinese people," 13 June 2018 There is a phenomenon of relativity known as time dilation, in which time appears to slow down almost to a stop for bodies that approach the speed of light. Jerry Adler, Newsweek, "Stephen Hawking, Master of the Universe: Our 1988 Cover Story on the Legendary Physicist," 14 Mar. 2018 The Hunger Games star has kept a relativity packed filming schedule in recent years, performing in movies including Mother! Lauren Rearick, Teen Vogue, "Jennifer Lawrence Says She's Taking a Year Off From Acting," 18 Feb. 2018 Given the linguistic relativity hypothesis, this means its theorizing about well-being is shaped by the nature of this language. Tim Lomas,, "1,000 words for happiness," 1 July 2018 On some level, this lines up nicely with the story of relativity. John Timmer, Ars Technica, "Gravitational waves and the slow pace of scientific revolutions," 30 June 2018 The finding not only validates Einstein's theory of relativity but also opens a new window on our knowledge of the universe. Sophia Chen, WIRED, "These Physicists Watched a Clock Tick for 14 Years Straight," 4 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'relativity.' 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 relativity

circa 1834, in the meaning defined at sense 1a

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Last Updated

27 Nov 2018

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The first known use of relativity was circa 1834

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English Language Learners Definition of relativity

physics : a theory developed by Albert Einstein which says that the way that anything except light moves through time and space depends on the position and movement of someone who is watching

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Britannica English: Translation of relativity for Arabic Speakers Encyclopedia article about relativity

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