guanidine
noun
gua·ni·dine ˈgwä-nə-ˌdēn 
: 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
Example Sentences
Recent Examples on the Web 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
Ashley Weatherford, The Cut, 15 May 2018 Word History
Etymology
International Scientific Vocabulary, from guanine
First Known Use
circa 1864, in the meaning defined above
Medical Definition
guanidine
noun
gua·ni·dine ˈgwän-ə-ˌdēn
: 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