reverse

Etymology 1

From Middle English revers, from Anglo-Norman revers, Middle French revers, and their source, Latin reversus, perfect passive participle of reversō, from re- + versō. Doublet of revers.

adj

1. Opposite, contrary; going in the opposite direction.
   We ate the meal in reverse order, starting with dessert and ending with the starter.
   The mirror showed us a reverse view of the scene.
2. Pertaining to engines, vehicle movement etc. moving in a direction opposite to the usual direction.
   He selected reverse gear.
3. (rail transport, of points) To be in the non-default position; to be set for the lesser-used route.
4. Turned upside down; greatly disturbed.
5. (botany) Reversed.
   a reverse shell
6. (genetics) In which cDNA synthetization is obtained from an RNA template.

adv

1. (now rare) In a reverse way or direction; in reverse; upside-down.
   The man was killed to feed his image fat / Within this pictured world that ran reverse, / Where miracles alone were ever plain. 1963, Donal Serrell Thomas, Points of Contact

noun

1. The opposite of something.
   We believed the Chinese weren't ready for us. In fact, the reverse was true.
2. The act of going backwards; a reversal.
   By a reverse of fortune, Stephen becomes rich. 1808, Charles Lamb, Specimens of the English Dramatic Poets Who Lived About the Time of Shakespeare
3. A piece of misfortune; a setback.
   Simon Forman was notorious in his day, and was a many of many reverses. 1936, Rollo Ahmed, The Black Art, London: Long, page 156
   In fact, though the Russians did not yet know it, the British had met with a reverse. 1990, Peter Hopkirk, The Great Game, Folio Society, published 2010, page 309
4. (numismatics) The tails side of a coin, or the side of a medal or badge that is opposite the obverse.
5. The side of something facing away from a viewer, or from what is considered the front; the other side.
6. The gear setting of an automobile that makes it travel backwards.
7. A thrust in fencing made with a backward turn of the hand; a backhanded stroke.
8. (surgery) A turn or fold made in bandaging, by which the direction of the bandage is changed.

Etymology 2

From Middle English reversen, from Anglo-Norman reverser, Middle French reverser, and their source, Latin reversō, from re- + versō.

verb

1. (transitive) To turn something around so that it faces the opposite direction or runs in the opposite sequence.
   to reverse the order of books on a shelf
   to reverse a portion of video footage
2. (transitive) To turn something inside out or upside down.
   A pyramid reversed may stand upon his point if balanced by admirable skill. 1672, William Temple, Essay on the Original and Nature of Government
3. (transitive) To transpose the positions of two things.
4. (transitive) To change totally; to alter to the opposite.
   All trends reverse eventually.
5. (obsolete, intransitive) To return, come back.
6. (obsolete, transitive) To turn away; to cause to depart.
7. (obsolete, transitive) To cause to return; to recall.
8. (law) To revoke a law, or to change a decision into its opposite.
   to reverse a judgment, sentence, or decree
   From March 30, LNER was running around 40% of its trains and had suspended its Aberdeen, Inverness and Hull services, although it reversed the latter decision after Hull Trains suspended operations. April 8 2020, “Network News: Emergency timetables and the number of services cut”, in Rail, page 15
9. (ergative, transport) To cause a mechanism to operate or move in the opposite direction to normal; to drive a vehicle in the direction the driver has the back.
   Richardson dropped into the six-foot between the two engines, ran for a few yards, grabbed Mitchell's engine, and swung himself up. Mitchell had got to his feet by this time, but he made no move. Richardson shut off steam, reversed her, and brought her to a stand. 1950 January, David L. Smith, “A Runaway at Beattock”, in Railway Magazine, page 54
10. (chemistry) To change the direction of a reaction such that the products become the reactants and vice-versa.
11. (rail transport, transitive) To place (a set of points) in the reverse position.
12. (rail transport, intransitive, of points) To move from the normal position to the reverse position.
13. (aviation, transitive) To engage reverse thrust on (an engine).
14. To overthrow; to subvert.
    Custom […] reverses even the distinctions of good and evil. a. 1729, John Rogers, Conformity to the World destructive of our Happiness
15. (computing) Short for reverse-engineer.
    Reversing is also heavily used in connection with malicious software, on both ends of the fence: […] 2011, Eldad Eilam, Reversing: Secrets of Reverse Engineering
    […] but in some instances where malware is proving to be difficult, reversing is needed. 2012, Christopher C. Elisan, Malware, Rootkits & Botnets: A Beginner's Guide, page 117