An Etymological Dictionary of Astronomy and Astrophysics

1. Similar or corresponding in some respect; having → analogy.
   

2. Biology: Similar in function but having different evolutionary origins, as the wings of birds and insects.
   

3. Chemistry: Similar in chemical properties and differing in chemical structure only with respect to one element or group.

See also: L. analogus, from Gk. analogos “proportionate,” → analogy.