An Etymological Dictionary of Astronomy and Astrophysics

1. To go from one country, region, or place to another.
   

2. To pass periodically from one region or climate to another, as certain birds, fishes, and animals.
   

3. Chem.: To move toward an electrode during electrolysis; (of atoms within a molecule) to change position (Dictionary.com).

Etymology (EN): From L. migratus p.p. of migrare “to move from one place to another,” ultimately from PIE *meig^h- “to move, go;” cf. Gk. ameibein “to change,” Iranian muž-, as below.

Etymology (PE): Mužidan, ultimately from Proto-Ir. *maij- “to move (to places);” cf. Parachi muž-, muš-, Yazghulami mûž- “to go,” mex^w-/max^wt- “to move, shake,” Gilaki maxtan “to stroll,” Gonâbâdi mejon “ague, shivering, shaking chills,” Sangesari moj; cognate with L. migrare “to move, go,” as below, Skt. niméghanāna- “moving down;” PIE *meig^h- “to move, go.”