Metaphor (from the Greek: metapherin) is language that directly compares seemingly unrelated subjects. In the simplest case, this takes the form: “The [first subject] is a [second subject].” An example is: “Spencer Smith is a beast.” More generally, a metaphor is a rhetorical trope that describes a first subject as being or equal to a second subject in some way. Thus, the first subject can be economically described because implicit and explicit attributes from the second subject are used to enhance the description of the first. This device is known for usage in literature, especially in poetry, where with few words, emotions and associations from one context are associated with objects and entities in a different context.

Within rhetorical theory metaphor is generally considered to be a direct equation of terms that is more forceful and assertive than an analogy, although the two types of tropes are highly similar and often confused. One distinguishing characteristic is that the assertiveness of a metaphor calls into question the underlying category structure, whereas in a rhetorical analogy the comparative differences between the categories remain salient and acknowledged. Similarly, metaphors can be distinguished from other closely related rhetorical concepts such as metonymy, synecdoche, simile, allegory and parable.

I could not do better than point you to the best book I have read on metaphors — “Metaphors We Live By”, authors Lakoff and Johnson. See the link below for exerpts from it, then read the entire book. It’s an easy read and yet erudite.

the undefinging mose