General opposites:
* Difficult: This is the most common and direct opposite of easy.
* Hard: Similar to difficult, but can also have a connotation of being physically demanding.
* Challenging: This implies something that requires effort and skill to overcome.
* Complex: This implies something intricate and multifaceted.
More specific opposites:
* Tough: This implies something that is physically or emotionally demanding.
* Intricate: This implies something that is detailed and complicated.
* Laborious: This implies something that requires a lot of effort and time.
* Unpleasant: This implies something that is not enjoyable or agreeable.
The best opposite of easy will depend on the specific situation and what you want to emphasize.