General Options:
* Semi-: This is a common prefix for "partly" or "half", so "semi-sweet" is a good general option.
* Partially-: This is a more literal and straightforward option.
More Specific Options:
* Sub-: Suggests "less than" or "below", implying the sweetness is lower than expected.
* Slightly-: Indicates a gentle sweetness, almost imperceptible.
* Moderately-: Suggests a balanced sweetness that isn't overwhelming.
Context-Specific:
The best option will depend on the context. For example, if you're describing a food product, you might use terms like:
* Low-sugar: Emphasizes the reduced sugar content.
* Unsweetened: If it's only slightly sweet, you might use this term to emphasize the minimal sweetness.
Ultimately, the best prefix depends on the specific meaning you want to convey and the context in which you're using it.