Definition of: homolog

(hom′ə·lôg, -log) noun
1. Something that answers in position, proportion, or type to, or has structural affinity with, something else; a member or form of a homologous series: Ethane is a homolog of methane.
2. Biol. A structure or part of an organism showing homology: The wing of a bat is the homolog of the arm of a man: distinguished from analog. Also hom′o·logue.