methylene blue

American  

noun

Chemistry, Pharmacology.

1. a dark-green, crystalline compound, C 1 6 H 1 8 ClN 3 S, that dissolves in water to form a deep-blue solution: used chiefly as a dye, as a bacteriological and biological stain, and as an antidote for cyanide poisoning.

---

methylene blue British  

noun

1. Also called: methylthionine chloride.  a dark-green crystalline compound forming a blue aqueous solution, used as a mild antiseptic and biological stain. Formula: C 16 H 18 N 3 SCl.3H 2 O

---

methylene blue Scientific  

1. A basic dye that forms a deep blue solution when dissolved in water. It is used as an antidote for cyanide poisoning and as a bacteriological stain. Chemical formula: C ₁₆ H ₁₈ N ₃ SCl.

---

Etymology

Origin of methylene blue

First recorded in 1885–90

Example Sentences

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.

From New York Times • Jan. 9, 2023

Recent studies show the effectiveness of methylene blue in increasing the body’s metabolic rate and as a treatment for Alzheimer’s patients.

From Textbooks • Jun. 9, 2022

Explain the use of methylene blue as an antidote for rotenone poisoning.

From Textbooks • Jun. 9, 2022

They tested a modified version of methylene blue — an outdated treatment for malaria, urinary tract infections and bipolar disorder — in a dosing and efficacy trial of 321 people with mild-to-moderate Alzheimer's disease.

From Nature • Jul. 13, 2011

Cultivated in skim milk in twenty-four hours at 37° C. Stain: aqueous methylene blue.

From The Bacillus of Long Life a manual of the preparation and souring of milk for dietary purposes, together with and historical account of the use of fermente by Douglas, Loudon