# thunderegg

> English word · Noun

## Definitions
1. A roughly spherical, nodule-like geological structure, similar to a geode, that is formed within a rhyolitic lava flow.

## Etymology
From thunder + egg.

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