The description of the word you requested from the astronomical dictionary is given below.
science, plural sciences
A science is a collection of knowledge and methods to check that knowledge for correctness and to get more knowledge. There are many sciences, such as physics, astronomy, mathematics, chemistry, geography, history, economics, and biology. A scientist is someone who does science for his work. A very important part of science is to check knowledge for correctness so that ideas that do not fit reality can be abandoned and only good ideas remain. Pseudo-sciences such as astrology and alchemy lack this self-correction.