# feynmanium

> English word · Noun

## Definitions
1. The hypothetical chemical element with atomic number 137.

## Etymology
From Feynman + -ium. After Richard Feynman, who used a back-of-the-envelope calculation using classical physics to determine that element 137 is the last stably neutrally charged element, as larger elements would need electrons traveling faster than light to become neutral. (This problem goes away when relativity is considered.)

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