/proh looh"zheuhn/ , n.
1. a preliminary written article.
2. an essay of an introductory nature, preliminary to a more profound work.
[ 1595-1605; prolusion- (s. of prolusio ) preliminary exercise, prelude, equiv. to prolus ( us ), ptp. of proludere ( pro- PRO- 1 + ludere to play; cf. PRELUDE) + -ion- -ION ]