• Today's Word

Postulate

🔊 Listen to the word Postulate

POS-chuh-layt

Definition

(verb) To suggest or assume something as a basis for reasoning or argument without prior proof.

Example

The scientist postulated that the mysterious signals were coming from a previously undiscovered layer of the atmosphere, a theory that took years to confirm.

Word Origin

Postulate derives from the Latin postulare, meaning “to demand” or “to claim,” rooted in poscere, meaning “to ask urgently.” In medieval logic and mathematics, a postulate was a foundational assumption that didn’t require proof — something demanded to be accepted as a starting point. Euclid’s famous geometric postulates, written around 300 BCE, are among the most influential examples in intellectual history.

Fun Fact

Euclid’s fifth postulate — the so-called “parallel postulate,” which states that parallel lines never meet — frustrated mathematicians for over 2,000 years. Countless scholars tried to prove it from first principles rather than accept it as an assumption, and all failed. It wasn’t until the 19th century that mathematicians realized you could simply reject the postulate and build entirely valid alternative geometries — leading to the development of non-Euclidean geometry, which later became essential to Einstein’s theory of general relativity.