AI Glossary
Underfitting
What does “Underfitting” mean?
Underfitting: When a model is too simple or has not trained enough, it misses the real patterns in the data and performs poorly even on its own training set. Common fixes are using a larger model, training longer or giving it better input features.

What is an example of “Underfitting”?
Fitting a straight line to data that clearly curves will underfit: the line misses the trend no matter how carefully it is placed.