* Few: If you're talking about quantity, "few" is the opposite of "most."
* Least: If you're talking about a comparative scale, "least" is the opposite of "most."
* All: If you're talking about a total amount, "all" is the opposite of "most."
* None: If you're talking about a complete lack, "none" is the opposite of "most."
Example:
* Most people like chocolate, but few like olives.
* The most expensive car is the Rolls Royce, but the least expensive is the Toyota.
* Most of the students passed the test, but all of them failed the final.
* Most people are friendly, but none of them were willing to help.
The best opposite word for "most" depends on the specific meaning you're trying to convey.