If "several" means "a few":
* Few: This is the most direct opposite.
* One: If you're talking about a single item.
* None: If there are absolutely no items.
If "several" means "a significant number":
* One or two: This emphasizes a very small number.
* Few: This emphasizes a limited number.
* None: This emphasizes the complete absence of items.
* Single: This emphasizes there's only one.
Example:
* Original sentence: Several students were absent.
* Opposite: Few students were absent.
It's important to consider the context of the sentence to choose the most accurate opposite.