An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

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.

From L. excursion- "a running forth, expedition," figuratively "an outset, opening," from excurrere "to run out," from → ex- "out" + currere "to run," → current.

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."

A geophysical event, distinguished from the → magnetic reversal, in which the Earth's magnetic field departs for a relatively short time from its usual near axial configuration, without establishing a reversed direction. During the excursion the intensity and direction of the Earth's magnetic field undergo drastic changes. Palaeomagnetic measurements have revealed that since the last full reversal the Earth's magnetic field has, for brief intervals, deviated from the behavior expected during "normal" secular variation.

→ geomagnetic; → excursion.