thinking about a past event or situation, often with a different opinion of it from the one you had at the time :
In retrospect, I think that I was wrong.
The decision seems extremely odd, in retrospect.
IN RETROSPECT
Meaning of IN RETROSPECT in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005