Etymology
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back off (v.)

"retreat, stop annoying someone," by 1938, from the verbal phrase, from back (v.) + off (adv.).

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back up (v.)

1767, "stand behind and support," from back (v.) + up (adv.). The meaning "move or force backward" is by 1834. Of water prevented from flowing, by 1837.

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get back (v.)

c. 1600 (intransitive) "to return;" 1808 (transitive) "to recover (something);" from get (v.) + back.(adv.). Meaning "retaliate" is attested by 1888.

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back seat (n.)

also back-seat, 1832, originally of coaches, from back (adj.) + seat (n.). Used figuratively for "less or least prominent position" by 1868. Back-seat driver "passenger who gives the driver unwanted advice" is attested by 1923.

You know him. The one who sits on the back seat and tells the driver what to do. He issues a lot of instructions, gives advice, offers no end of criticism and doesn't do a bit of work. ["The Back Seat Driver," Wisconsin Congregational Church Life, May 1923]
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back down (v.)

in figurative sense of "withdraw a charge," 1859, American English, from the notion of descending a ladder, etc. (such a literal sense is attested by 1849); from back (v.) + down (adv.).

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shut up (v.)

c. 1400, "keep from view or use, render inaccessible" early 15c., "to lock up, confine," from shut (v.) + up (adv.). The meaning "cause to stop talking" is from 1814 (Jane Austen). The intransitive meaning "cease from speaking" is from 1840, also as a command to be silent, sometimes colloquialized in print as shuddup (1940). Put up or shut up "defend yourself or be silent" is U.S. slang, by 1868.

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civil disobedience (n.)

coined 1866 by Thoreau as the title of his essay originally published (1849) as "Resistance to Civil Government."

If the alternative is to keep all just men in prison, or give up war and slavery, the State will not hesitate which to choose. If a thousand men were not to pay their tax-bills this year, that would not be a violent and bloody measure, as it would be to pay them, and enable the State to commit violence and shed innocent blood. This is, in fact, the definition of a peaceable revolution, if any such is possible. [Thoreau]
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au revoir (interj.)

1690s, French, "good-bye for now," literally "to the seeing again." From au "to the" (see au) + revoir "see again, see in turn" (Old French reveoir, 12c.), from Latin revidere, from re- "back, again" (see re-) + videre "to see" (see vision).

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lingua franca (n.)

1620s, from Italian, literally "Frankish tongue." A stripped-down Italian peppered with Spanish, French, Greek, Arabic, and Turkish words, it began as a form of communication in the Levant. The name probably is from the Arabic custom, dating back to the Crusades, of calling all Europeans Franks (see Frank). In 17c. English sources also known as Bastard Spanish.

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contra-dance (n.)

"dance by four couples placed opposite to each other and making the same steps and figures," 1803, from French contre-danse, altered from English country dance by folk etymology from French contra "against," suggested by the arrangement of the partners in the dance. The dances and the name were taken up in France c. 1720s and from there passed to Spain and Italy (Spanish, Italian contra danza) then back to English.

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