late 14c., mutacioun, "action or process of changing," from Old French mutacion (13c.), and directly from Latin mutationem (nominative mutatio) "a changing, alteration, a turn for the worse," noun of action from past-participle stem of mutare "to change" (from PIE root *mei- (1) "to change, go, move"). The genetics sense "process whereby heritable changes in DNA arise" is from 1894. The linguist's i-mutation is attested from 1874; earlier was i-umlaut (1869), from German, for which mutation was Sweet's English substitute.
1900 in the biological sense, "individual or form which has arisen by or undergone (genetic) mutation," from Latin mutantem (nominative mutans) "changing," present participle of mutare "to change" (from PIE root *mei- (1) "to change, go, move"). In the science fiction sense, it is attested by 1954. As an adjective from 1903.