美国学术出版社科学技术字典，Academic Press Dictionary of Science & Technology

1. the systematic observation of natural events and conditions in order to discover facts about them and to xxxxulate laws and principles based on these facts. 2. the organized body of knowledge that is derived from such observations and that can be verified or tested by further investigation. 3. any specific branch of this general body of knowledge, such as biology, physics, geology, or astronomy.

http://www.gly.uga.edu/railsback/1122sciencedefns.html

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美国传统词典，The American Heritage® Dictionariry of the English Language, 4th edition

1.
1. The observation, identification, dexxxxion, experimental investigation, and theoretical explanation of phenomena.
2. Such activities restricted to a class of natural phenomena.
3. Such activities applied to an object of inquiry or study.
2. Methodological activity, discipline, or study: I've got packing a suitcase down to a science.
3. An activity that appears to require study and method: the science of purchasing.
4. Knowledge, especially that gained through experience.
5. Science Christian Science.

[Middle English, knowledge, learning, from Old French, from Latin scientia, from sciēns, scient-, present participle of scīre, to know.]

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McGraw-Hill科技百科全书，McGraw-Hill Encyclopedia of Science and Technology, 5th edition

Science

In common usage the word science is applied to a variety of disciplines or intellectual activities which have certain features in common. Usually a science is characterized by the possibility of making precise statements which are susceptible of some sort of check or proof. This often implies that the situations with which the special science is concerned can be made to recur in order to xxxx themselves to check, although this is by no means always the case. There are observational sciences such as astronomy or geology in which repetition of a situation at will is intrinsically impossible, and the possible precision is limited to precision of dexxxxion.

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哥伦比亚百科全书，Columbia Electronic Encyclopedia

science [Lat. scientia=knowledge]. For many the term science refers to the organized body of knowledge concerning the physical world, both animate and inanimate, but a proper definition would also have to include the attitudes and methods through which this body of knowledge is xxxxed; thus, a science is both a particular kind of activity and also the results of that activity.

http://www.answers.com/topic/science

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佐治亚大学，University of Georgia

Science is the concerted human effort to understand, or to understand better, the history of the natural world and how the natural world works, with observable physical evidence as the basis of that understanding1. It is done through observation of natural phenomena, and/or through experimentation that tries to simulate natural processes under controlled conditions.

http://www.gly.uga.edu/railsback/1122science2.html#WHATISSCIENCE