Final answer:
A codon is a group of three nitrogen bases that makes up a code word of the genetic code.
Step-by-step explanation:
A codon is a group of three nitrogen bases in nucleic acids that makes up a code "word" of the genetic code. The genetic code consists of a sequence of nitrogen bases in DNA or RNA. There are 4 nitrogen bases: adenine (A), cytosine (C), guanine (G), and thymine (T) (or uracil, U, in RNA). When these nitrogen bases are combined in groups of three, they form codons.