A period of time in which suitable action can achieve success.
2013, Martina Hyde, Is the pope Catholic? (in The Guardian, 20 September 2013)http://www.theguardian.com/commentisfree/2013/sep/20/is-pope-catholic-atheists-gay-people-abortion
The Lord moves in mysterious ways – though not a thousandth as mysterious as those of his senior personnel from time to time – so there is no earthly possibility of predicting how long the window of opportunity enjoyed by Pope Francis is likely to be.