# methylthioninium

> English word · Noun

## Definitions
1. The heterocyclic cation 3,7-bis(dimethylamino)-phenothiazin-5-ium, which is the basis of methylene blue

## Etymology
From methyl + thionine + -ium (“quaternary ammonium compound”).

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