Which prefix means "not" or "opposite" in Latin?

The prefix that means "not" or "opposite" in Latin is "im." This prefix is often used in words to indicate negation or the opposite of the root word it modifies. For instance, in the word "impossible," the prefix "im" conveys the idea of "not possible." Understanding this prefix is crucial in recognizing the meaning of various words in English, especially in the context of structured language education where many terms can be broken down into their constituents.

In contrast, the other options do not convey the meaning of negation. The prefix "anti" generally signifies "against" or "opposite," but not in an outright negating sense. "Pre" refers to "before," indicating a time-related aspect rather than opposition. Lastly, "uni" means "one," further illustrating that these prefixes serve distinct functions and meanings that are separate from the idea of negation.