noun. with regard to genetics, the degree to which the impacts of an allele are cultivated in the people retaining it, displayed as the fraction or percentage of people carrying that allele who cultivated the trait correlated with it. If all people who retain a specific dominant allele grow the correlated trait, the allele is considered to show complete, or 100%. In contrast, incomplete takes place whenever some people with a specific allele don't grow the correlated trait.
PENETRANCE: "The level of penetrance is actually rather small in this case."