Pronunciation: (sī'tu-sēn", -zēn", -sin), [key]
a pyrimidine base, C4H5N3O, that is one of the fundamental components of DNA and RNA, in which it forms a base pair with guanine. Symbol: C Cf. cytidine, cytidine monophosphate.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.