Looking on the internet deeply has found these results:

momentous event is the most popular phrase on the web.

momentous trend 11,380 results on the web	momentous event 1414,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
A momentous occasion, the first time in history... To Lily and Marshall and their momentous step forward into adulthood. You initiated momentous changes in the Soviet Union and did much to end the Cold War. This is indeed a momentous day for the five kingdoms. I mean, getting married should be momentous. You are most welcome on this momentous occasion. The Soviet occupation had even more momentous consequences for Latvia. This is momentous news, Mr. President.	This is a momentous event, and it is incredible to think that from 1989 to 2004 we have been part of this Parliament that has brought about such major historic changes. This wedding is a momentous event for our House of Scientists and for our entire town which isn't on the map yet. That was a momentous event for the new Member States and indeed for the Union as a whole. In the former presidency negotiations were started to enlarge the Union a momentous event The discovery of a new particle is a momentous event. These five years have been marked by major political and institutional changes and momentous events in Europe and around the world. together with a decision on which countries should join the euro, the establishment of a central bank, arguably an even more momentous event.

momentous trend

11,380 results on the web

momentous event

1414,000 results on the web

More popular!

A momentous occasion, the first time in history...
To Lily and Marshall and their momentous step forward into adulthood.
You initiated momentous changes in the Soviet Union and did much to end the Cold War.
This is indeed a momentous day for the five kingdoms.
I mean, getting married should be momentous.
You are most welcome on this momentous occasion.
The Soviet occupation had even more momentous consequences for Latvia.
This is momentous news, Mr. President.

This is a momentous event, and it is incredible to think that from 1989 to 2004 we have been part of this Parliament that has brought about such major historic changes.
This wedding is a momentous event for our House of Scientists and for our entire town which isn't on the map yet.
That was a momentous event for the new Member States and indeed for the Union as a whole.
In the former presidency negotiations were started to enlarge the Union
a momentous event
The discovery of a new particle is a momentous event.
These five years have been marked by major political and institutional changes and momentous events in Europe and around the world.
together with a decision on which countries should join the euro, the establishment of a central bank, arguably an even more momentous event.