noun. A pyrimidine base, C₄H₅N₃O, that is the constituent of DNA and RNA involved in base-pairing with guanine.

noun. A pyrimidine (C4H5N3O) which is one of the four major basic components of DNA and RNA in most organisms, forming glyosides with ribose and deoxyribose. It is the basic component of cytidine, deoxycytidine, cytosine, cytidine monophosphate, and derivatives of those compounds.

noun. A base, C4H5N3O, which pairs with guanine in DNA and RNA.

noun. a base found in DNA and RNA and derived from pyrimidine; pairs with guanine

"The position of the atoms in cytosine could be determined, because under the action of an oxidizing agent this substance breaks down into biuret and oxalic acid, and this elucidation of its constitution was soon followed by its synthesis."

cytosine arabinoside  

pyrimidine  

accelerant  adenine  alanine  amino-acid  carboxylate