Answer
Nitrogen monoxide.
Work Step by Step
It is named according to the rules of naming binary molecular compounds. A prefix is used to name according to the number of atoms present and the name of the second element ends with '-ide'. Thus, in $NO$, one atom of nitrogen is present (the prefix mono is not added to the first element in a compound) and one atom of oxygen is present ( Monoxide). Thus, Nitrogen monoxide.
