Done after the fact; applying to events that have previously transpired.(adverb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "retroactively" in a sentence
"It didn't always make sense, but you could tell that the writers were sincere about laying the longterm groundwork, or at least successful in retroactively paying off random moments from the earlier films."
"I'm not a lawyer, but I think the concept of applying a law retroactively is contrary both to the letter and the spirit of our laws and Constitution."
"Earlier this year, Finance Minister Yuval Steinitz said he was considering changing terms retroactively — meaning the government could extract better terms on previously assigned leases."