cysteine
noun
cys·te·ine ˈsi-stə-ˌēn 
: a crystalline sulfur-containing amino acid C3H7NO2S readily oxidizable to cystine
Example Sentences
Recent Examples on the Web The new treatment is an inexpensive, over-the-counter supplement called N-acetyl cysteine, or NAC, that is widely available. 
Cezary Podkul, WSJ, 28 Dec. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The subjects were then asked to swallow placebo or L-cysteine tablets containing vitamin supplements. BostonGlobe.com, 19 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 That amino acid is supposed to be cysteine, and has been in all humans examined to this point. Mark Johnson And Kathleen Gallagher, Milwaukee Journal Sentinel, 21 Dec. 2010 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 See More
Cezary Podkul, WSJ, 28 Dec. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The subjects were then asked to swallow placebo or L-cysteine tablets containing vitamin supplements. BostonGlobe.com, 19 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 That amino acid is supposed to be cysteine, and has been in all humans examined to this point. Mark Johnson And Kathleen Gallagher, Milwaukee Journal Sentinel, 21 Dec. 2010 The researchers received funding from Catapult Cat Oy, which sells the L-cysteine supplements. Andrew Stuttaford, National Review, 20 Aug. 2020 See More Word History
Etymology
International Scientific Vocabulary, from cystine + -ein
First Known Use
1884, in the meaning defined above
Medical Definition
cysteine
noun
cys·teine ˈsis-tə-ˌēn
: a sulfur-containing amino acid C3H7NO2S occurring in many proteins and glutathione and readily oxidizable to cystine —abbreviation Cys