General Opposites:
* Useless: This is the most straightforward and common opposite.
* Futile: Implying something is pointless or ineffective.
* Ineffective: Not producing the desired result.
* Worthless: Having no value or use.
Context-Specific Opposites:
* Harmful: If something is useful, its opposite could be something that causes damage.
* Dangerous: If something is useful for a specific purpose, its opposite might be something that poses a risk.
* Redundant: If something is useful because it's necessary, its opposite might be something unnecessary.
Opposite in the sense of "purpose":
* Ornamental: Something that is decorative rather than functional.
* Aesthetic: Something that is beautiful but not necessarily practical.
It's important to consider the specific situation to determine the most appropriate opposite word for "useful."