The quality or condition of being tedious; tediousness or boredom.
The condition or quality of being tiresome, wearisome, boring, or monotonous; tediousness.
Tedium is a state of boredom or monotony.
Sitting in a really dull traffic school class where you already know all the material and aren't interested in learning or reviewing it is an example of tedium.
Origin of tedium
Latin taedium from taedēre to weary