late 15c., from Middle French mobile (14c.), from Latin mobilis "movable, easy to move; loose, not firm," figuratively, "pliable, flexible, susceptible, nimble, quick; changeable, inconstant, fickle," contraction of *movibilis, from movere "to move" (see move, v.). Sociology sense from 1927. Mobile home first recorded 1940.

early 15c. in astronomy, "outer sphere of the universe," from mobile, adj.; the artistic sense is first recorded 1949 as a shortening of mobile sculpture (1936). Now-obsolete sense of "the common people, the rabble" (1670s) led to mob, n..