Answer
NI$_{3}$ - Nitrogen Triiodide.
Work Step by Step
1. First, begin by writing the name of the first element. N -Nitrogen.
2. Since, NI$_{3}$ is a molecular compound (two non-metals joined together), we have to use the appropriate prefix for the second element.
3. Note that the second element , iodine, has three atoms. This means we have to use the prefix "tri" and change iodine's ending to iodide.
4. Combine the two names to get $$Nitrogen Triiodide.$$