Meaning of homologous

ho•mol•o•gous

1. having the same or a similar relation; corresponding, as in relative position or structure.
2. corresponding in structure and in origin, but not necessarily in function: The wing of a bird and the foreleg of a horse are homologous.
3. having the same alleles or genes in the same order of arrangement: homologous chromosomes.
4. of the same chemical type, but differing by a fixed increment of an atom or a constant group of atoms: Methyl and ethyl alcohols are homologous.
5. pertaining to an antigen and its specific antibody.