"to banish, send out of one's native country," 1768, modeled on French expatrier "banish" (14c.), from ex- "out of" (see ex-) + patrie "native land," from Latin patria "one's native country," from pater (genitive patris) "father" (see father (n.); also compare patriot). Related: Expatriated; expatriating. The noun is by 1818, "one who has been banished;" main modern sense of "one who chooses to live abroad" is by 1902.
<a href="https://www.etymonline.com/word/expat">Etymology of expat by etymonline</a>
Harper, D. (n.d.). Etymology of expat. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/expat