prōlūsĭo, ōnis, f. [proludo],
a prelude , transf., a preliminary exercise , trial , essay , Cic. de Or. 2, 80, 325; id. Div. in Caecil. 14, 47
prōlūsiō ōnis, f pro+LVD-, a prelude, preliminary exercise, trial, essay . ...
An Elementary Latin Dictionary