a property which is shown by some alleles. When the alleles are present in a heterozygous state they produce a different phenotype from that produced by either allele in the homozygous state.
A phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in a heterozygote. Blood type is an example of codominance.
Equal effect on the phenotype of two alleles of the same locus (as opposed to recessive and dominant).