Homologous \Ho*mol"o*gous\, a. [Gr. ? assenting, agreeing; ? the same + ? speech, discourse, proportion, ? to say, speak.]

Having the same relative position, proportion, value, or structure. Especially:
   (a) (Geom.) Corresponding in relative position and proportion.

In similar polygons, the corresponding sides, angles, diagonals, etc., are homologous. --Davies & Peck (Math. Dict.).
   (b) (Alg.) Having the same relative proportion or value, as the two antecedents or the two consequents of a proportion.
   (c) (Chem.) Characterized by homology; belonging to the same type or series; corresponding in composition and properties. See Homology, 3.
   (d) (Biol.) Being of the same typical structure; having like relations to a fundamental type to structure; as, those bones in the hand of man and the fore foot of a horse are homologous that correspond in their structural relations, that is, in their relations to the type structure of the fore limb in vertebrates.

Homologous stimulus. (Physiol.) See under Stimulus.

Source: Webster's Revised Unabridged Dictionary (1913)