Analogy

Part of speech: noun (n.)

1. A resemblance of relations; an agreement or likeness between things in some circumstances or effects, when the things are otherwise entirely different. Thus, learning enlightens the mind, because it is to the mind what light is to the eye, enabling it to discover things before hidden.

2. A relation or correspondence in function, between organs or parts which are decidedly different.

3. Proportion; equality of ratios.

4. Conformity of words to the genius, structure, or general rules of a language; similarity of origin, inflection, or principle of pronunciation, and the like, as opposed to pl. analogies. Johnson.