General:
* Dull: This is a classic choice, implying a lack of excitement or interest.
* Tedious: This suggests something that is long and tiresome.
* Monotonous: This implies a lack of variation or change, making something repetitive and boring.
* Uninteresting: This is a straightforward adjective meaning lacking in interest or excitement.
More specific:
* Wearisome: This emphasizes the feeling of exhaustion or fatigue caused by something boring.
* Mind-numbing: This suggests something that makes you feel mentally numb or unengaged.
* Tiresome: Similar to "wearisome," but with a focus on the feeling of being tired.
* Stale: This implies something that is old, outdated, and lacking in freshness.
* Lackluster: This describes something that is dull and lacking in brilliance or excitement.
Figurative:
* Sleep-inducing: This implies something so boring it makes you want to fall asleep.
* Soporific: Similar to "sleep-inducing," but with a more formal tone.
* Humdrum: This refers to something that is ordinary, routine, and lacking in excitement.
The best adjective to use depends on the specific context and the effect you want to create.