Astronomy Answers: From the Astronomical Dictionary
The description of the word you requested from the astronomical dictionary is given
the star ⇒
astèr = [Greek] star
A star is a ball of (mostly) hydrogen gas that is so massive that
- is held together by its own gravitation.
- has such a high gas pressure and temperature in its center that
nuclear fusion of hydrogen to helium occurs there, which provides the
energy that makes the star shine brightly.