Source : Webster's Revised Unabridged Dictionary (1913)

Analogy \A*nal"o*gy\, n.; pl. {Analogies}. [L. analogia, Gr. ?,
   fr. ?: cf. F. analogie. See {Analogous}.]
   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.

   Note: Followed by between, to, or with; as, there is an
         analogy between these objects, or one thing has an
         analogy to or with another.

   Note: Analogy is very commonly used to denote similarity or
         essential resemblance; but its specific meaning is a
         similarity of relations, and in this consists the
         difference between the argument from example and that
         from analogy. In the former, we argue from the mere
         similarity of two things; in the latter, from the
         similarity of their relations. --Karslake.

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

   3. (Geom.) Proportion; equality of ratios.

   4. (Gram.) 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 {anomaly}. --Johnson.

Source : WordNet®

analogy
     n 1: an inference that if things agree in some respects they
          probably agree in others
     2: drawing a comparison in order to show a similarity in some
        respect; "the operation of a computer presents and
        interesting analogy to the working of the brain"; "the
        models show by analogy how matter is built up"
     3: the religious belief that between creature and creator no
        similarity can be found so great but that the
        dissimilarity is always greater; language can point in the
        right direction but any analogy between God and humans
        will always be inadequate [syn: {doctrine of analogy}]
        [ant: {apophatism}, {cataphatism}]