Usually in ML context generalization means anytime a model makes a prediction on unseen (not in the training set) inputs. Usually you do CV to see how well your

Usually in ML context generalization means anytime a model makes a prediction on unseen (not in the training set) inputs. Usually you do CV to see how well your model generalized because you limit the training data seen, predict unseen inputs that you know the answer to, and see how far off the prediction is.