n. (Abbr. U)
A pyrimidine base, C4H4N2O2, that is an essential constituent of RNA.
[UR(EA) + AC(ETIC) + -il, substance relating to.]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.