methylene blue


: a basic thiazine dye C16H18ClN3S·3H2O used especially as a biological stain, an antidote in cyanide poisoning, and an oxidation-reduction indicator

Examples of methylene blue in a Sentence

Recent Examples on the Web To gauge the fat content of the cream brought by farmers, the dairy would insert methylene blue in a sample and waited for its lactic acid to dissolve the color. Joseph Berger,, 10 Jan. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'methylene blue.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1882, in the meaning defined above

Time Traveler
The first known use of methylene blue was in 1882

Dictionary Entries Near methylene blue

Cite this Entry

“Methylene blue.” Dictionary, Merriam-Webster, Accessed 23 Sep. 2023.

Kids Definition

methylene blue

meth·​y·​lene blue
: a dye used as a biological stain and to reverse the effects of cyanide poisoning

Medical Definition

methylene blue

: a basic thiazine dye C16H18ClN3S·3H2O used in the treatment of methemoglobinemia, as an antidote in cyanide poisoning, as a biological stain, and as an oxidation-reduction indicator

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