homology
n. uncountable C1 Advanced ho·mol·o·gy
n. a similarity between two things because they share a common origin or history. In biology, it means two different animals have the same body part because they are related.
n. the condition of being similar in structure, function, or origin because of common ancestry. In mathematics, it refers to a relationship between two objects that preserves their essential properties.
The wings of a bat and a bird show structural homology.
Biologists use homology to determine how different species are related by comparing their skeletal structures.
While the specific functions of the limbs may have diverged through evolution, the underlying homology of the bones provides clear evidence of a shared vertebrate ancestor.