is the use of systematic methods of empirical investigation, the analysis of data, theoretical thinking, and the logical assessment of arguments to develop a body of knowledge about a particular subject matter.

Science.

Explanation:

First, let us fill in the gap in the question above;

PS: The word in that is capitalized is the missing word in the question.

''SCIENCE is the use of systematic methods of empirical investigation, the analysis of data, theoretical thinking, and the logical assessment of arguments to develop a body of knowledge about a particular subject matter '.

Science is the understanding of nature (physical, and biological sciences) and the study of people's behaviour (social sciences) so as to improve the society. When someone is studying science, the person will have specific things to do for example doing researches observing and so on.

There is another part of science that studies living things so as to improve the quality of lives and that is called the health science.