* Aburrido: This is the most common and general antonym, meaning boring or dull.
* Triston: This translates to sad or gloomy, suggesting a lack of joy.
* Desagradable: This means unpleasant or disagreeable, highlighting a negative experience.
* Monótono: This refers to something lacking variety or excitement, being repetitive and monotonous.
* Insípido: This translates to tasteless or bland, referring to a lack of excitement or flavor.
The best antonym for "divertido" will depend on the specific context and the nuance you want to convey.