ex·cur·sion / ikˈskərzhən/ • n. 1. a short journey or trip, esp. one engaged in as a leisure activity: an excursion to Mount Etna fig. an excursion into theology. ∎  [usu. as adj.] a trip at reduced rates: a popular excursion fare for travel during the next two weeks.2. technical an instance of the movement of something along a path or through an angle. ∎  a deviation from a regular pattern, path, or level of operation.3. archaic a digression.4. archaic a military sortie (see alarum).DERIVATIVES: ex·cur·sion·ist / -ist/ n.

excursion †escape; sally, sortie XVI; journey from home XVII. — L. excursiō, -ōn-, f. excurs-, pp. stem of excurrere run out, issue forth, f. EX-1 + currere; see COURSE, -ION.
Hence excursionist XIX. So excursus XIX.