A pulsar is a star that spins very fast and cannot be seen but produces regular radio signals.
pulsar in British English
(ˈpʌlˌsɑː)
noun
any of a number of very small extremely dense objects first observed in 1967, which rotate very rapidly and emit very regular pulses of polarized radiation, esp radio waves. They are thought to be neutron stars formed following supernova explosions
Word origin
C20: from puls(ating st)ar, on the model of quasar
pulsar in American English
(ˈpʌlˌsɑr; ˈpʌlsər)
noun
any of several celestial objects, thought to be rotating neutron stars, which emit electromagnetic radiation, esp. radio waves, at short and very regular intervals
abbrev. PSR
Word origin
pulse1 + -ar
Examples of 'pulsar' in a sentence
pulsar
The neutron star hasn't been a pulsar for at least that long.
Niven, Larry & Pournelle, Jerry THE MOAT AROUND MURCHESON'S EYE (1993)