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.
"yielding gain, highly profitable," early 15c., from Old French lucratif "profitable" and directly from Latin lucrativus "gainful, profitable," from lucratus, past participle of lucrari "to gain, win, acquire," from lucrum "gain, profit" (see lucre). Related: Lucratively; lucrativeness.
c. 1200, maistren, "to get the better of, prevail against; reduce to subjugation," from master (n.) and also from Old French maistriier, Medieval Latin magistrare. Meaning "acquire complete knowledge of, overcome the difficulties of, learn so as to be able to apply or use" is from 1740s. Related: Mastered; mastering.