# double descent

CEFR C2 · Noun

Source: https://englishreference.com/word/double-descent
Updated: 2026-09-28

## Definition

a surprising pattern where an AI model's test mistakes go down, spike at a critical size, and then go down again as it gets even larger.

For teachers: the phenomenon in overparameterized models where test risk decreases, peaks near the interpolation threshold where parameters equal sample size, and decreases again.

## Examples

- Engineers observed double descent when making the neural network bigger actually improved its accuracy on tests.
- The discovery of double descent reconciled classical statistical trade-offs with the modern success of massive deep learning models.
- In modern overparameterized regimes, double descent demonstrates that implicit regularization in gradient descent guides overfitted networks toward minimum-norm solutions.

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