1. Similarities in some respects between things that are otherwise dissimilar and a comparison based on such similarities.
2. A form of logical inference or an instance of it, based on the assumption that if two things are known to be alike in some respects, then they must be alike in other respects.
3. The similarities in function, but differences in evolutionary origin, of body structures in different organisms; for example, the wing of a bird is analogous to the wing of an insect, since both are used for flight, however, there is no common ancestral origin in the evolution of these structures.

While the wings of birds are modified skeletal forelimbs, insect wings are extensions of the body wall.

5. The process by which words or morphemes are re-formed or created on the model of existing grammatical patterns in a language, often leading to a greater regularity in paradigms, as evidenced by "helped" replacing "holp" and "holpen" as the past tense and past participle of "help" on the model of verbs; such as, "yelp, yelped", and "yelped".
6. Etymology: from Latin analogia which came from Greek analogia, "proportion", from Greek ana-, "upon, according to" + Greek logos, "ratio"; also, "word, speech, reckoning".

In transportation engineering, a conceptual model of traffic flow based on the behavior of fluids.

The intuitive power of this model is expressed in common terms; such as, "flow" and "bottleneck", but the "fluid-flow analogy" is also used to construct sophisticated models of traffic behavior.