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1560s, plural of Middle English metaphisik, methaphesik (late 14c.), "branch of speculation which deals with the first causes of things," from Medieval Latin metaphysica, neuter plural of Medieval Greek (ta) metaphysika, from Greek ta meta ta physika "the (works) after the Physics," title of the 13 treatises which traditionally were arranged after those on physics and natural sciences in Aristotle's writings. The name was given c.70 B.C.E. by Andronicus of Rhodes, and was a reference to the customary ordering of the books, but it was misinterpreted by Latin writers as meaning "the science of what is beyond the physical." See meta- + physics. The word originally was used in English in the singular; plural form predominated after 17c., but singular made a comeback late 19c. in certain usages under German influence.
The field in philosophy that studies ultimate questions, such as whether every event has a cause and what things are genuinely real.