homology

noun

1. 1

   A homologous relationship.

2. 2

   A theory associating a system of groups to each topological space.

3. 3

   A certain system of groups associated to a chain complex.

4. 4

   The relationship between the elements in the same group of the periodic table, or between organic compounds in a homologous series.

5. 5

   A correspondence of structures in two life forms with a common evolutionary origin, such as flippers and hands.

6. 6

   The presence of the same series of bases in related genes.