What is the prefix meaning of word benign?

The prefix of the word "benign" is "be-." However, it's important to note that "be-" in this case doesn't have a distinct meaning on its own. It's an example of a prefix that has lost its original meaning over time and become part of the word's root.

The root of "benign" is "bene," which comes from Latin and means "good" or "well." So, "benign" essentially means "well-natured" or "harmless."