Ho-mŏl'o-goŭs, a.

a. [Gr. ὁμόλογος, assenting, agreeing, from ὁμός, the same, and λόγος, speech, discourse, proportion, λέγειν, to say, speak; Fr. homologue.] 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, &c., are homologous. Math. Dict.

(b.) (Alg.) Having the same relative proportion or value, as the two antecedents or the two consequents of a proportion. (c.) (Chem.) Being of the same chemical type or series; differing by a multiple or arithmetical ratio in certain constituents, while the physical qualities are wholly analogous, with small relative differences, as if corresponding to a series of parallels; as, the species in the group of alcohols are said to be homologous. (d.) (Zool.) Being of the same typical structure; having like relations to a fundamental type of 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. Dana.