Each user of the term uses it in a different context each time he uses it and thereby shows transparently that the meaning is different in each use. The meaning differs from user to user and for one user at different times. It will be impossible to reduce the meaning of the term to a single simple fundamental sense. The shotgun compilation of a few meanings will not lead to any conclusion except that meaning is uncertain. It might be possible for a single author to write a monograph and nail down a meaning in a context. See also the essay "Creative Mind" by Dorothy L. Sayers, in The Whimsical Christian (Collier Books, Macmillan Publishing Company, New York). ISBN 0-02-096430-7.
Contains an interesting discussion of some populist (and other) misunderstandings arising from (as it were) "knee-jerk" reliance on the scientific method; includes a good discussion of the differences between specific scientific usage of terms and lay-folks' misunderstanding by confusion with the vernacular definitions.
Cheers!