late 14c., "not subject to (a rule, law, authority, etc.)," from Old French exempt (13c.) and directly from Latin exemptus, past participle of eximere "remove, take out, take away; free, release, deliver, make an exception of," from ex "out" (see ex-) + emere "to buy," originally "to take," from PIE root *em- "to take, distribute." Also in Middle English in a more general sense, "taken away, cut off (from), removed (from)."
c. 1400, exempten, "to relieve, to free or permit to be free" (from some requirement or condition, usually undesirable), from Anglo-French exempter, from exempt (adj.); see exempt (adj.). Related: Exempted; exempting.