# hesperium

> English word · Noun

## Definitions
1. A rejected name for plutonium. (Esperium chemical symbol: Es)

## Etymology
From Italian Esperio after a Greek name of Italy + -ium, Ancient Greek Ἑσπερία (Hespería, “land of the west”).

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