When it comes to tasks that are challenging or difficult to complete, the phrase "tough assignment" is a common way to describe them. However, there are plenty of synonyms that can be used to convey the same meaning, such as "daunting task," "difficult mission," "challenging undertaking," "arduous project," or "demanding duty." Each of these phrases highlights the complexity and difficulty of the task at hand, emphasizing the fact that it requires a significant degree of effort and skill to successfully complete. Whether you're facing a tough assignment at work, school, or in your personal life, these synonyms can help you describe the challenge in more specific terms and communicate your needs more clearly to others.