# isomer

> English word · Noun · IPA /ˈaɪ.sə.mə/ · frequency rank #55,520

## Definitions
1. Any of two or more compounds with the same molecular formula but with different structure.
2. Any of two or more atomic nuclei with the same mass number and atomic number but with different radioactive properties.

## Etymology
From iso- + -mer.

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