React and Reverse

react

Show a response or a reaction to something.
- synonyms: respond
Act against or in opposition to.
- usage: "She reacts negatively to everything I say"
- synonyms: oppose
Undergo a chemical reaction; react with another substance under certain conditions.
- usage: "The hydrogen and the oxygen react"

(v.t.) To act or perform a second time; to do over again; as, to react a play; the same scenes were reacted at Rome.
(v.i.) To act upon each other; to exercise a reciprocal or a reverse effect, as two or more chemical agents; to act in opposition.
(v.i.) To return an impulse or impression; to resist the action of another body by an opposite force; as, every body reacts on the body that impels it from its natural state.

Webster's Revised Unabridged Dictionary

(Military) REACT stands for rapid execution and combat targeting

Department of Defense Dictionary of Military and Associated Terms. 31 January 2011.

reverse

A relation of direct opposition.
- usage: "we thought Sue was older than Bill but just the reverse was true"
- synonyms: contrary, opposite
The gears by which the motion of a machine can be reversed.
- synonyms: reverse gear
An unfortunate happening that hinders or impedes; something that is thwarting or frustrating.
- synonyms: reversal, setback, blow, black eye
The side of a coin or medal that does not bear the principal design.
- synonyms: verso
American football. ( a running play in which a back running in one direction hands the ball to a back running in the opposite direction)
Turning in the opposite direction.
- synonyms: reversion, reversal, turnabout, turnaround

Change to the contrary.
- usage: "The trend was reversed"; "the tides turned against him"; "public opinion turned when it was revealed that the president had an affair with a White House intern"
- synonyms: change by reversal, turn
Turn inside out or upside down.
- synonyms: turn back, invert
Rule against.
- usage: "The Republicans were overruled when the House voted on the bill"
- synonyms: overrule, overturn, override, overthrow
Cancel officially.
- usage: "He revoked the ban on smoking"; "lift an embargo"; "vacate a death sentence"
- synonyms: revoke, annul, lift, countermand, repeal, overturn, rescind, vacate
Reverse the position, order, relation, or condition of.
- usage: "when forming a question, invert the subject and the verb"
- synonyms: invert

Directed or moving toward the rear.
- usage: "a rearward glance"; "a rearward movement"
- synonyms: rearward
Of the transmission gear causing backward movement in a motor vehicle.
- usage: "in reverse gear"
Reversed (turned backward) in order or nature or effect.
- synonyms: inverse

(a.) Hence, to overthrow; to subvert.
(a.) That which appears or is presented when anything, as a lance, a line, a course of conduct, etc., is reverted or turned contrary to its natural direction.
(a.) To turn back; to cause to face in a contrary direction; to cause to depart.
(a.) The act of reversing; complete change; reversal; hence, total change in circumstances or character; especially, a change from better to worse; misfortune; a check or defeat; as, the enemy met with a reverse.
(a.) That which is directly opposite or contrary to something else; a contrary; an opposite.
(a.) The back side; as, the reverse of a drum or trench; the reverse of a medal or coin, that is, the side opposite to the obverse. See Obverse.
(a.) To overthrow by a contrary decision; to make void; to under or annual for error; as, to reverse a judgment, sentence or decree.
(a.) To change totally; to alter to the opposite.
(a.) Reversed; as, a reverse shell.
(v.i.) To return; to revert.
(a.) To turn upside down; to invert.
(a.) To cause to return; to recall.
(v.i.) To become or be reversed.
(a.) A thrust in fencing made with a backward turn of the hand; a backhanded stroke.
(a.) Turned upside down; greatly disturbed.
(a.) A turn or fold made in bandaging, by which the direction of the bandage is changed.
(a.) Turned backward; having a contrary or opposite direction; hence; opposite or contrary in kind; as, the reverse order or method.

Webster's Revised Unabridged Dictionary

reverse is an informal name for a reverse repurchase agreement.