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.

1520s, Latin, literally "let the buyer beware;" see caveat and second element of exempt (adj.).

Proto-Indo-European root meaning "to take, distribute." 

It forms all or part of: assume; consume; emption; example; exemplar; exemplary; exemplify; exempt; exemption; impromptu; peremptory; pre-emption; premium; presume; presumption; prompt; pronto; ransom; redeem; redemption; resume; sample; sejm; subsume; sumptuary; sumptuous; vintage.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit yamati "holds, subdues;" Latin emere "buy," originally "take," sumere "to take, obtain, buy;" Old Church Slavonic imo "to take;" Lithuanian imu, imti "to take."

For the sense shift from "take" to "buy" in the Latin verbs, compare Old English sellan "to give," source of Modern English sell "to give in exchange for money;" Hebrew laqah "he bought," originally "he took;" and colloquial English I'll take it for "I'll buy it." 

mid-15c., "free, exempt" (from taxes, tithes, sin, etc.), from Latin immunis "exempt from public service, untaxed; unburdened, not tributary," literally "not paying a share," from assimilated form of in- "not, opposite of" (see in- (1)) + munis "performing services" (compare municipal), from PIE *moi-n-es-, suffixed form of root *mei- (1) "to change, go, move." Specific modern medical sense of "exempt (from a disease)," typically because of inoculation, is from 1881, a back-formation from immunity. Immune system attested by 1917.

1560s, "bestow lasting fame upon, exempt from oblivion," from immortal + -ize. Perhaps modeled on French immortaliser. The literal sense "endow with immortality" is from 1630s in English. Related: Immortalized; immortalizing.

"day given to pastime or diversion, a day exempt from work," c. 1600, from play (v.) + day.

c. 1200, "excused, exempt, free, clear" (of debt, obligation, penalty, etc.), from Old French quite, quitte "free, clear, entire, at liberty; discharged; unmarried," and directly from Medieval Latin quitus, quittus, from Latin quietus "free" (in Medieval Latin "free from war, debts, etc."), also "calm, resting" (from PIE root *kweie- "to rest, be quiet").

From mid-13c. as "deprived of." From c. 1300 of real property, "exempt from taxes or other dues or claims."

late Old English scotfreo "exempt from royal tax," from scot (n.) "royal tax" + freo "free" (see free (adj.)).

legal Latin, literally "in the form of a poor person" (thus exempt from certain court fees, etc.), 1590s; see form (n.) + pauper (n.).