codominance
This term is used exclusively within the field of genetics to describe a specific relationship between alleles. It is frequently contrasted with incomplete dominance, where the resulting phenotype is a blend or intermediate of the two parents, whereas codominance results in both traits appearing distinctly and simultaneously.
As a technical scientific term, it is almost always used as an uncountable noun. It describes a biological mechanism or state rather than a discrete object that can be counted.
Meanings
A genetic phenomenon in which two different alleles at a single locus are both fully expressed in the phenotype of a heterozygote, resulting in a trait where both parental characteristics are visible simultaneously.
The AB blood group in humans is a classic example of codominance, as both A and B antigens are expressed on the red blood cells.