1.
The duration of an event or state is the time during which it happens or exists.
He was given the task of protecting her for the duration of the trial...
Courses are of two years' duration.
N-UNCOUNT: oft the N of n
2.
If you say that something will happen for the duration, you mean that it will happen for as long as a particular situation continues.
His wounds knocked him out of combat for the duration.
PHRASE: PHR after v