• (n.) Investigation of things by the analogy they bear to each other. • (n.) an argument from the cause to the effect; an a priori argument.
A·nal'o·gism noun [ Greek ... course of reasoning, from ... to think over, to calculate] 1. Logic an argument from the cause to the effect; an a priori argument. Johnson. 2. Investigation of things by the analogy they bear to each other. Crabb. 
reasoning or argument by analogy.