Learner's definition of BRINK
: the edge at the top of a steep cliff — usually used figuratively to refer to a point that is very close to the occurrence of something very bad or (less commonly) very good
He nearly lost everything because of his drug addiction, but his friends helped to pull him back from the brink.
The two nations are on the brink of war. [=are very close to war]
a city on the brink of financial disaster
Doctors may be on the brink of finding a cure for this disease.
a young actress who is on the brink of a brilliant career
The other team brought them to the brink of defeat. [=came very close to defeating them]
an animal that has been brought/pulled back from the brink of extinction