General Opposite:
* Unhelpful: This is the most direct opposite, meaning not providing assistance.
* Harmful: This implies causing damage or negative consequences.
Specific Opposites:
* Hindering: This implies actively preventing progress or success.
* Obstructive: Similar to hindering, but suggests blocking or impeding.
* Counterproductive: This means having the opposite effect of what is intended.
* Detrimental: This emphasizes causing harm or damage.
The best opposite word for "helpful" depends on the specific situation and the intended meaning.