Why KNN Algorithm is called as Lazy Learner?

KNN algorithm is the Classification algorithm. It is also called as K Nearest Neighbor Classifier. K-NN is a lazy learner because it doesn’t learn a discriminative function from the training data but memorizes the training dataset instead. There is no training time in K-NN. The prediction step in K-NN is expensive. Each time we want to make a prediction, K-NN is searching for the nearest neighbors in the entire training set. An eager learner has a model fitting or training step. A lazy learner does not have a training phase.