Quiz: Remember the definition of mal de mer?
c.1500, a back-formation from adoption or else from Middle French adopter or directly from Latin adoptare "take by choice, choose for oneself, select, choose" (especially a child). Originally in English also of friends, fathers, citizens, etc. Sense of "to legally take as one's own child" and that of "to embrace, espouse" a practice, method, etc. are from c.1600. Related: Adopted; adopting.