Answer
-11
Work Step by Step
Two numbers that are the same distance from 0 but lie on opposite sides of 0 are called opposites of each other. Furthermore, we know that the sum of a number $a$ and its opposite $-a$ is 0.
We know that $|-11|=-(-11)=11$.
Therefore, the opposite of $|-11|$ is $-11$, because $|-11|+(-11)=11-11=0$.