The definition of science is the observation, identification, description, experimental investigation, and theoretical explanation of phenomena. It is in particular used in activities applied to an object of inquiry or study. [Ref]
Any of the branches of natural or physical sciences
A particular branch of knowledge
Knowledge, as of facts or principles; knowledge gained by systematic study
Skill, esp. reflecting a precise application of facts or principle; proficiency
The word Science comes from Latin word "scientia" meaning "knowledge" and in broadest sense it is any systematic knowledge-base or prescriptive practice being capable of resulting in prediction. This is why science is termed as highly skilled technique or practice.
However, in more contemporary terms, science is a system of acquiring knowledge based on scientific process or method in order to organize body of knowledge gained through research.
Science remains a continuing effort on the part of human being to discover and increase knowledge through research. Scientist make observations, record measureable data related to their observations, analyze the information in hand in order to construct theoretical explanations of phenomenon involved.
The methods involve in scientific research include making hypothesis and do experimentation to test the hypothesis under controlled conditions. In this process, scientists publish their works so other scientists can do similar experiments in may be different conditions to further strengthen the reliability of results.
Scientific fields are broadly divided into natural sciences (to study natural phenomenons) and social sciences (to study human behavior and societies). However, in both of these divisions, the knowledge must be obtained through observations and capable of being tested for its validity by other researchers working under similar conditions. There are some other disciplines like health science and engineering that are grouped into interdisciplinary and applied sciences.
Most scientific investigations use some form of the scientific method. A scientific method tries to explain the events of nature in reproducible way and allow using these reproductions to form predictions.
Scientists make observations of natural phenomenon and than through experimentation they try to stimulate natural events under controlled conditions. Based on observations, a scientist may generate a model and then attempt to describe or depict the phenomenon in terms of mathematical or logical representation. Scientist will than gather the empirical evidence and will generate his/her hypothesis to explain the phenomenon.
This description is used to form predictions which in turn will be tested by experiment or observations using scientific method. Evaluations are made which may prove hypothesis acceptable or discard it altogether or recommend modifications.