Definition of might-have-been in US English:
 might-have-been
nounˈmaɪd əv ˌbɪnˈmīd əv ˌbin
informal A past possibility that no longer applies.
 fretting about might-have-beens won't get us anywhere
 Example sentencesExamples
-  The main theme rounded out, speaking of loss, reminding of might-have-beens.
 -  But the shoulders have widened and the appetite for victory sharpened by a few years' reflection on the might-have-beens.
 -  The might-have-beens preoccupy us as a random natural disaster never can.
 -  You could say this was a match about might-have-beens.
 -  The other might-have-been concerns the 1990 World Cup finals in Italy.
 -  A letter from an old flame fluttered to the welcome mat this week, tinged with the rosy glow of nostalgia and giving off a faint melancholy whiff of might-have-beens.
 -  Counterfactual history - the history of might-have-beens - then becomes much more than an exercise in subjective speculation.
 -  A subtle gesture, a quick flight into rage, that sassy line of dialogue - all these might-have-beens can keep bit-players from becoming stars, or stars becoming legends.
 -  This opens up a lost world of might-have-beens.
 -  Still, there are few might-have-beens that taste as good as this one.
 -  He had his share of abandoned projects, what the author refers to as ‘Leonardo's might-have-beens.’
 -  One is left to reflect on the many might-have-beens and the extreme narrowness between victory and a severe setback.