Definition of homologous
1a : having the same relative position, value, or structure: such as (1) biology : exhibiting biological homology (2) biology : having the same or allelic genes with genetic loci usually arranged in the same order <homologous chromosomes>b chemistry : belonging to or consisting of a chemical series (see series 6) whose successive members have a regular difference in composition especially of one methylene group
2 biology : derived from or developed in response to organisms of the same species <a homologous tissue graft>
Did You Know?
In his famous discussion of the panda's thumb, Stephen Jay Gould carefully explains how this thumb is not homologous to the human thumb. Although the two digits are used in much the same way (the panda's thumb is essential for stripping bamboo of its tasty leaves, the staple of the panda's diet), the panda's thumb developed from a bone in its wrist and is an addition to the five "fingers" of its paw. The tiny stirrup and anvil bones of our inner ear, however, do seem to be homologous with the bones that allow a garter snake to swallow a frog whole.
Origin and Etymology of homologous
Greek homologos agreeing, from hom- + legein to say — more at legend
First Known Use: 1660
Medical Definition of homologous
1a: having the same relative position, value, or structure: as (1): exhibiting biological homology (2): having the same or allelic genes with genetic loci usually arranged in the same order <homologous chromosomes>b: belonging to or consisting of a chemical series whose members exhibit homology
2a: derived from or involving organisms of the same species <homologous tissue grafts>—compare autologous, heterologous 1b: relating to or being immunity or a serum produced by or containing a specific antibody corresponding to a specific antigen
Seen and Heard
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