A phenocopy is an individual whose phenotype (generally referring to a specific trait) is environmentally induced to mimic the phenotype of an organism whose phenotype was genetically determined. These changes are not mutations, as the underlying DNA sequence of the phenocopy is not altered. As such, these changes are not heritable.

A good example is in the Vanessa genus of butterflies, who may adopt the phenotype of butterflies living in either Lapland or Syria, depending on which region to which they are introduced.