For something lacking in excitement or interest:
* Bland: (e.g., "The food was bland and tasteless.")
* Tedious: (e.g., "The meeting was tedious and went on forever.")
* Monotonous: (e.g., "The speaker's voice was monotonous.")
* Uninspiring: (e.g., "The movie was uninspiring and forgettable.")
* Boring: (e.g., "The lecture was boring and I couldn't focus.")
* Uninteresting: (e.g., "The book was uninteresting and I stopped reading it.")
* Lackluster: (e.g., "The team's performance was lackluster.")
* Unremarkable: (e.g., "The city was unremarkable and had no character.")
For something lacking in brightness or shine:
* Matte: (e.g., "The paint was matte and had no gloss.")
* Faded: (e.g., "The colors were faded and washed out.")
* Dim: (e.g., "The light was dim and made it hard to see.")
* Gloomy: (e.g., "The sky was gloomy and gray.")
* Flat: (e.g., "The fabric was flat and lifeless.")
For something lacking in sharpness or keenness:
* Blunt: (e.g., "The knife was blunt and wouldn't cut.")
* Unfocused: (e.g., "The camera lens was unfocused and the picture was blurry.")
* Vague: (e.g., "The instructions were vague and unclear.")
More figurative words:
* Uninspiring: (e.g., "The art exhibit was uninspiring and left me feeling empty.")
* Drab: (e.g., "The room was drab and depressing.")
* Mediocre: (e.g., "The movie was mediocre and didn't live up to its hype.")
* Unremarkable: (e.g., "The food was unremarkable and nothing special.")
The best word to use will depend on the specific context and the nuance you want to convey.