* Container: The opposite of a cup as a container could be plate, bowl, jar, or box, depending on what you're holding.
* Shape: The opposite of a cup's shape could be flat, rectangular, or spherical, depending on the specific shape you're comparing it to.
* Function: If you're thinking about the function of a cup for drinking, the opposite could be fork, knife, spoon, or any other utensil that serves a different purpose.
To find the most accurate opposite, it's important to consider the specific context in which you're using the word "cup."