WordNet (r) 3.0 (2006):

pulsar
    n 1: a degenerate neutron star; small and extremely dense;
         rotates very fast and emits regular pulses of polarized
         radiation

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "pulsar":
   Beehive, Cepheid variable, Hertzsprung-Russell diagram, Hyades,
   Messier catalog, NGC, Pleiades, Seven Sisters, absolute magnitude,
   binary star, black hole, double star, dwarf star, fixed star,
   giant star, globular cluster, gravity star, magnitude,
   main sequence star, mass-luminosity law, neutron star, nova,
   open cluster, populations, quasar, quasi-stellar radio source,
   radio star, red giant star, relative magnitude, sky atlas,
   spectrum-luminosity diagram, star, star catalog, star chart,
   star cloud, star cluster, stellar magnitude, supernova,
   variable star, white dwarf star