# Bayes' theorem

> English word · Proper noun

## Definitions
1. A theorem expressed as an equation that describes the conditional probability of an event or state given prior knowledge of another event.

## Etymology
Named after English mathematician Thomas Bayes (1701–1761), who developed an early formulation. The modern expression of the theorem is due to Pierre-Simon Laplace, who extended Bayes's work but was apparently unaware of it.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/bayes-theorem