In logic, begging the question is a type of fallacy occurring in deductive reasoning in which the proposition to be proved is assumed implicitly or explicitly in one of the premises. However, more recently, "begs the question" has been used as a synonym for "raises the question."

A quantum leap is properly an instantaneous change, which may be either large or small. In physics, it is the smallest possible changes that are of particular interest. In vernacular usage, however, the term is often taken to imply an abrupt large change.