Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

cysteine

play
noun cys·te·ine \ˈsis-tə-ˌēn\

Definition of cysteine

  1. :  a crystalline sulfur-containing amino acid C3H7NO2S readily oxidizable to cystine



Origin of cysteine

International Scientific Vocabulary, from cystine + -ein


First Known Use: 1884


Medical Dictionary

cysteine

play
noun cys·teine \ˈsis-tə-ˌēn\

Medical Definition of cysteine

  1. :  a sulfur-containing amino acid C3H7NO2S occurring in many proteins and glutathione and readily oxidizable to cystine—abbreviation Cys




Learn More about cysteine


Seen and Heard

What made you want to look up cysteine? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

a timid, meek, or unassertive person

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

alt-5746713d76276

Which of these is a synonym of nonplus?

reduce disapprove perplex soothe
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ