early 15c., obteinen, "to get or acquire, inherit, gain, conquer," from Old French obtenir "acquire, obtain" (14c.) and directly from Latin obtinere "hold, hold fast, take hold of, get possession of, acquire," from ob "in front of" (though perhaps intensive in this case; see ob-) + tenere "to hold," from PIE root *ten- "to stretch." Intransitive sense of "be prevalent or customary, be established in practice" is from 1610s. Related: Obtained; obtaining.
1670s, "to obtain right to land" by securing letters patent, from patent (n.). The meaning "obtain a copyright to an invention" is recorded by 1822, from the earlier meaning "obtain exclusive right or monopoly" (1789), a privilege granted by the Crown via letters patent. Related: Patented; patenting.
1520s, "obtain by force or compulsion; wrest away by oppressive means," from Latin extortus, past participle of extorquere "obtain by force," literally "to wrench out," from ex "out" (see ex-) + torquere "to twist" (from PIE root *terkw- "to twist"). Related: Extorted; extorting. As a past-participle adjective from early 15c.
"the obtaining or trying to obtain something by craft or deception," 1610s, from Latin obreptionem (nominative obreptio) "a creeping or stealing on," noun of action from past-participle stem of obrepere "to creep on, creep up to," from ob "on, to" (see ob-) + repere "to creep" (see reptile). Opposed to subreption, which is to obtain something by suppression of the truth. Related: Obreptious.