Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

relativity

play
noun rel·a·tiv·i·ty \ˌre-lə-ˈti-və-tē\

Simple 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

Full Definition of relativity

plural rel·a·tiv·i·ties

  1. 1 a :  the quality or state of being relative b :  something that is relative

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

  3. 3 a :  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

  4. 4 :  relativism 1b



Seen and Heard

What made you want to look up relativity? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

February 9, 2016

marked by high spirits and laughter

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image1037863653

Which of the following refers to thin, bending ice, or to the act of running over such ice?

pince-nez duvet kittly-benders spindrift
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ