gua·​ni·​dine ˈgwä-nə-ˌdēn How to pronounce guanidine (audio)
: a base CH5N3 derived from guanine that in the form of its hydrochloride acts as a parasympathetic stimulant and is used especially to denature proteins

Examples of guanidine in a Sentence

Recent Examples on the Web The drug is a derivative of guanidine, a compound found in Goat's Rue, an herbal medicine long used in Europe. Allison Aubrey, NPR, 22 Apr. 2024 Metformin, a synthesized version of guanidine, was first used as a diabetes treatment in France in the 1950s and was finally approved in the United States in 1995. Liz Seegert, Fortune Well, 4 May 2023 Galega contains guanidine, which, in 1918, was shown to lower blood glucose. Liz Seegert, Fortune Well, 4 May 2023 Using a main ingredient of sodium hydroxide, lithium hydroxide, potassium hydroxide, or guanidine hydroxide, chemical relaxers break and restructure the bonds in curly hair so that the hair becomes weaker and straight. Ashley Weatherford, The Cut, 15 May 2018

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

Word History


International Scientific Vocabulary, from guanine

First Known Use

circa 1864, in the meaning defined above

Time Traveler
The first known use of guanidine was circa 1864

Dictionary Entries Near guanidine

Cite this Entry

“Guanidine.” Dictionary, Merriam-Webster, Accessed 18 Jul. 2024.

Medical Definition


gua·​ni·​dine ˈgwän-ə-ˌdēn How to pronounce guanidine (audio)
: a base CH5N3 that is derived from guanine, is found especially in young tissues, and is used in organic synthesis and that in the form of its hydrochloride CH5N3·HCl is used as a drug to enhance acetylcholine activity
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