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"arrangement," 1890, from verbal phrase set up, attested from c.1200 as "to make ready for use" and from 1950 (in pugilism) as "to bring (someone) to a vulnerable position;" from set (v.) + up (adv.). The verbal phrase also can mean "to establish" (early 15c.) and "put drinks before customers" (1880).
[most senses apparently fr the setting up of billiard or pool balls to ensure a special or a trick shot]