[ kwey-zahr, -zer, -sahr, -ser ]
/ ˈkweɪ zɑr, -zər, -sɑr, -sər /

noun Astronomy.

one of over a thousand known extragalactic objects, starlike in appearance and having spectra with characteristically large redshifts, that are thought to be the most distant and most luminous objects in the universe.



Have the Words of the Day from October 19–25, 2020, made an indelible mark on your memory? Take the quiz to find out!
Question 1 of 7
What does “clement” mean?
Also called quasi-stellar object.

Origin of quasar

1960–65; quas(i-stell)ar, in quasi-stellar radio source, the first type of quasar discovered
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for quasar

  • The direction of polarization for a quasar is determined by the accretion disk surrounding it.

    The Black Hole Tango|Matthew R. Francis|November 24, 2014|DAILY BEAST

British Dictionary definitions for quasar

/ (ˈkweɪzɑː, -sɑː) /


any of a class of extragalactic objects that emit an immense amount of energy in the form of light, infrared radiation, etc, from a compact source. They are extremely distant and their energy generation is thought to involve a supermassive black hole located in the centre of a galaxy

Word Origin for quasar

C20: quas (i-stell) ar (object)
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

Scientific definitions for quasar

[ kwāzär′ ]

Short for quasi-stellar radio source. A compact, starlike celestial body with a power output greater than our entire galaxy. Believed to be the oldest and most distant objects ever detected, quasars are billions of light-years from Earth and moving away from us at nearly 80 percent of the speed of light. For this reason, quasars are highly important to astronomers' understanding of the early universe. Little is currently understood about the nature of quasars; one theory suggests that they are produced by giant black holes destroying enormous amounts of matter, causing the subsequent ejection of radiation along their north and south poles. Many astronomers believe that quasars represent an early stage in the evolution of galaxies such as our own. See also blazar Seyfert galaxy.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.