Answer
To name a molecular compound, we would keep the first element's name as-is and only add a prefix if there is more than one atom of that element in the compound. For the second element in the compound, we add a prefix reflecting how many atoms of that element is present in the compound.
Nitrogen oxide, therefore, would not be a valid name for NO because the nitrogen part would be correct but the oxide should have a prefix of $mono-$ to denote that there is only one oxygen atom in this compound. The "correct" name for this compound should be "nitrogen monoxide."
Work Step by Step
To name a molecular compound, we would keep the first element's name as-is and only add a prefix if there is more than one atom of that element in the compound. For the second element in the compound, we add a prefix reflecting how many atoms of that element is present in the compound.
Nitrogen oxide, therefore, would not be a valid name for NO because the nitrogen part would be correct but the oxide should have a prefix of $mono-$ to denote that there is only one oxygen atom in this compound. The "correct" name for this compound should be "nitrogen monoxide."