The description of the word you requested from the astronomical dictionary is given below.
the 'U‧ni‧verse, plural universes
The Universe is all space put together, with everything that's in it. Because of the finite age of the Universe and the finite speed with which light and other information carriers move, we can have knowledge of even in principle only a finite part of the Universe. That part is also often called the Universe (or the Visible Universe). For more information about the Universe, see the Universe Page of the Universe Family Tree.