Given a confusion matrix, there's all kind of metrics: Accuracy, Precision, Recall/Sensitivity, Specificity.
But I haven't seen any name for the ratio between the TN (True Negative) and the sum of TN + FN (False Negative): $$ \frac{TN}{TN + FN} $$
Is there a name for it? If not - why isn't it important enough to have a name?