1. A mysterious, "quasistellar", or star-like, object in a galaxy's core which is very small, very bright, and very distant.

Most quasars are strong sources of radio energy.

2. An exceptionally powerful, yet very compact extragalactic object, whose exact nature is still uncertain.

Observations suggest that quasars may be the hyperactive nuclei of galaxies, while theory indicates that the high luminosity which is 100 to 1,000 times that of normal galaxies, could be associated with a supermassive black hole.

1. 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.
2. A blend of quasi and stellar.

• Quasi: As if; as though; as it were; in a manner sense or degree; having some resemblance to.
• Stellar: Relating to, consisting of, or like a star or stars.

1. A small dense star that emits brief intense bursts of visible radiation, radio waves, and X-rays, and is generally believed to be a rapidly rotating neutron star.
2. A blend of pulse and quasar.

• Pulse: A brief temporary change in a normally constant quantity, e.g. in a voltage, or a series of intermittent disturbances that are regular in form and frequency of occurrence.
• Quasar: A compact object in space, usually with a large red shift indicating extreme remoteness, that emits huge amounts of energy, sometimes equal to the energy output of an entire galaxy.