Minority class Machine Learning
noun phrase
Definition: In imbalanced learning, the class that contains comparatively fewer instances than other classes in the dataset; in such settings, minority classes are typically underrepresented and more difficult for models to learn reliably [Gao et al. 2025].
Example in context: “The class imbalance problem poses a critical challenge in high-stakes applications such as fraud detection, where the minority class often represents rare but consequential cases.” [Sun et al. 2025]
Synonyms: underrepresented class; rare class
Related terms: class imbalance; majority class; imbalanced dataset; oversampling; undersampling