In The Structure of Scientific Revolutions, Thomas Kuhn coins a new use of the word "paradigm."
Literally, "paradigm" means an example, a pattern or a model. For example, the TGV is the paradigm of a fast, efficient electric passenger train.
Kuhn's new-in-1962 use of the word is for a scientific achievement that defines the legitimate problems for further research in that field. According to Kuhn, there are two qualifications that scientific paradigms must have: first, the achievement the paradigm arises from must be "sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity," and, second, it is "sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners to resolve."
A scientific paradigm represents a sort of world-view from which scientists work at a given time. For example, Isaac Newton's Principia Mathematica, Lavoisier's Chemistry and Aristotle's Physica all provided the scientists of those times with new paradigms from which to view natural phenomena. Those works are closely associated with expressions like "Newtonian mechanics" and "Aristotelian dynamics." Some other well known paradigms are "Copernican astronomy," "Einsteinian mechanics" and that of Maxwell's equations for electromagnetism.