Position:
* Over: This is the most common antonym when referring to position.
* Above: This is another common antonym when referring to position.
* On top of: This is more specific and emphasizes the direct contact between the two things.
* On: This is similar to "over" but can sometimes be used for items that are on a surface.
Other meanings:
* Over: This can also be an antonym for "under" when referring to exceeding a limit, such as "under age" vs. "over age."
* Above: This can be an antonym when referring to a higher level or standard, such as "underperforming" vs. "above average."
* More than: This is a more general antonym for "under" when referring to quantity.
Example:
* "The ball is under the table." The antonym would be "over the table", "above the table", or "on top of the table".
* "He is under 18 years old." The antonym would be "over 18 years old".
* "The company is underperforming." The antonym could be "above average" or "outperforming".
Therefore, to determine the correct antonym, you need to consider the specific context in which "under" is used.