An Etymological Dictionary of Astronomy and Astrophysics

1. A short trip or outing to some place, usually for a special purpose and with the intention of a prompt return.
   

   2. Physics: The displacement of a body or a point from a mean position or neutral value, as in an oscillation (Dictionary.com). → geomagnetic excursion.

Etymology (EN): From L. excursion- “a running forth, expedition,” figuratively “an outset, opening,” from excurrere “to run out,” from → ex- “out” + currere “to run,” → current.

Etymology (PE): Zocâr, literally “wander out, " from zo- “out,” → ex-, + câr “to come and go, wander,” related to car-, caridan “to psature, graze;” (Karingân) cârumé “excursion, walking around,” (Sorxé) câqâle, (Sangesar, Semnân) ceqala “excursion;” Av. car- “to come and go, wander;” cf. Skt. car- “to move, walk, go;” Gk. pelomai “I move;” L. colere “to till, cultivate;” PIE root *k^welH- “to move, turn, wander.”