Thanks for your answers. However, I did a little bit of 'googling', and I found out that some do use the word "emergent meeting" Here are some instances:
1. Minutes of the EMERGENT MEETING OF THE
EXECUTIVE COMMITTEE OF THE CHAMBER
2.
BJP asks PM to convene emergent meet on Amarnath deaths How many dead pilgrims carried mandatory health certificates?
3. The meeting of a Lodge called to elect a candidate, and confer the Degrees in a case of emergency, or for any other sudden and unexpected cause, has been called an Emergent Meetings The term is not very common, but it has been used by Brother W. S. Mitchell and a few other writers.
Just a few examples. So, thanks again for all your replies. I hope my thread somehow gives you a little something as well :-D;-)