εἴσ-βᾰσις · eis-basis — LSJ
an entrance, ways of entrance, embarkation, introductory process, first stage
an entrance, εἰσβάσεις μηχανώμενοι devising ways of entrance, E. IT 101; embarkation, Th. 7.30, D.C. 41.42; introductory process, first stage of a magical operation, PMag.Par. 1.397.