• Webster's Revised Unabridged Dictionary
    • v. i Retroact To act backward, or in return; to act in opposition; to be retrospective.
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Century Dictionary and Cyclopedia
    • retroact To act backward; have a backward action or influence; hence, to act upon or affect what is past.
    • ***
Chambers's Twentieth Century Dictionary
    • v.i Retroact rē-trō-akt′ to act backward, or in return or opposition, or on something past or preceding
    • ***


Webster's Revised Unabridged Dictionary
Pref. retro- + act,
Chambers's Twentieth Century Dictionary
L. retroactus, retroagĕreretro, backward, agĕre, actum, to do.


In literature:

EPITAPH, n. An inscription on a tomb, showing that virtues acquired by death have a retroactive effect.
"The Devil's Dictionary" by Ambrose Bierce
Milner contended for a five years' retroactive franchise, with provisions to secure adequate representation for the mining districts.
"The Great Boer War" by Arthur Conan Doyle
Priority, retroaction, the opposition of agents, unity, stability and rhythm.
"Delsarte System of Oratory" by Various
There's an extradition treaty coming, but then there'd have to be a retroactive clause to do you any good.
"Murder in Any Degree" by Owen Johnson
This bill raises the salaries of members from $1000 to $1500, an increase of fifty per cent, and is retroactive.
"Have faith in Massachusetts; 2d ed." by Calvin Coolidge
The apotheosis will be retroactive, nay, it has already taken place.
"The Life of Reason" by George Santayana
In other words, was the principle, newly recovered, to be applied retroactively?
"Stephen A. Douglas" by Allen Johnson
You see we made the law sufficiently retroactive to grab the whole bunch.
"Alice in Blunderland" by John Kendrick Bangs
That woman could not retroact and touch the memory of Ida.
"Stories by American Authors, Volume 7" by Various
Retroactive effect given to the law is a crime.
"The Writings Of Thomas Paine, Complete" by Thomas Paine

In poetry:

Done with the varying distress
Of retroactive consciousness!
Set free to feel the joy unknown
Of Life and Love beyond my own!
"Eternal Me" by Charlotte Perkins Stetson Gilman

In news:

Romney administration would undo defense sequester ' retroactively .
Romney would undo defense cuts ' retroactively .
Even if Congress makes the Bush tax cuts retroactive , the fiscal cliff could still slow down the economy if Americans skeptical that they'll be spared slow consumer and business spending.
"Romney 'retired retroactively ' from Bain Capital".
If you come in late for work some morning, tell the boss you are arriving retroactively and already have a lot of work done.
Mitt Romney retired from Bain Capital ' retroactively ,' Ed Gillespie says.
Graham retroactively resigns from Channel 7.
Lansing won't retroactively take things away — from themselves.
The Phillies on Tuesday placed star righthander Roy Halladay on the disabled list retroactive to Monday with a strained muscle in his right shoulder and back.
The Mets on Tuesday announced the team has placed pitcher Mike Pelfrey on the 15-day disabled list, retroactive to April 22, with swelling in his right, pitching elbow.
Senator Jay Rockefeller (D-West Virginia) is reportedly steering the secretive Senate Intelligence Committee to give retroactive immunity to telecoms that helped the government secretly spy on Americans.
Early in President Barack Obama's administration, the EPA retroactively rejected a permit for a surface mine in West Virginia.
Scarponi's ban began retroactively Oct 1 and expires the end of this month.
Retroactive pact includes 3-percent pay hikes, city-paid insurance.
Decision should not apply retroactively to Michigan inmates who have already exhausted most appeals.

In science:

Proactive interference refers to prior learning interfering with subsequent learning; retroactive interference refers to post hoc learning confounding the prior learning (Wickens & Hollands, 2000).
Human Information Processing with the Personal Memex
This contributes an effective additional force field in the vicinity of R α , which in turn retroacts on β , leading to an induced hydrodynamic interaction that remains finite at all times.
Screening of hydrodynamic interactions for polyelectrolytes in salt solution
Del Vecchio D, Ninfa A, Sontag E: Modular cell biology: retroactivity and insulation.
TinkerCell: Modular CAD Tool for Synthetic Biology
Read-once CFTP may be viewed as a retroactive stopping rule.
How to Couple from the Past Using a Read-Once Source of Randomness
Abhijit S. thanks for support provided by NASA of the retroactive analysis WFPC2 photometry zero-points through grant HST-AR-09216.01A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
The Hubble Constant: A Summary of the HST Program for the Luminosity Calibration of Type Ia Supernovae by Means of Cepheids