The quality or state of being tedious: Tediousness. (Merriam – Webster)
A tedious period of time. (Merriam – Webster)
The quality of being boring for a long time. (Cambridge Dictionary)
The quality or state of being wearisome; irksomeness; tediousness. (Dictionary.com)
If you talk about the tedium of a job, task, or situation, you think it is boring and rather frustrating. (Collins Dictionary)
The Tedium is the Message: How Adult Animation Visualises Monotony.
Thought there was just one type of boredom? Think again: Scientists identify a FIFTH form of tedium.