Complete dominance occurs in genetics as a relationship in genes between the alleles. The dominant allele will completely mitigate any effect the recessive allele has in determining the outcome of the gene.
An example of complete dominance occurring in nature is when a violet flower inherits a purple color and white color allele from each parent; every offspring flower will have a purple color. The purple color allele (PP) completely overpowers the white color allele (pp) showcasing its complete dominance in terms of genetics. The violet flower will have a purple hue regardless if the flower is (PP) or (Pp).