metaphor

 A metaphor is a figure of speech that, for rhetorical effect, directly refers to one thing by mentioning another. It may provide  clarity or identify hidden similarities between two different ideas.

Metaphors are often compared with other types of figurative language, such as antithesis, hyperbole, metonymy, and simile. One of the most commonly cited examples of a metaphor in English literature comes from the "All the world's a stage" monologue from As You Like It:

All the world's a stage,

And all the men and women merely players;

They have their exits and their entrances

And one man in his time plays many parts,

His Acts being seven ages. At first, the infant...

—William Shakespeare, As You Like It, 

This quotation expresses a metaphor because the world is not literally a stage, and most humans are not literally actors and actresses playing roles. By asserting that the world is a stage, Shakespeare uses points of comparison between the world and a stage to convey an understanding about the mechanics of the world and the behavior of the people within it.

The word metaphor itself is a metaphor, coming from a Greek term meaning "transference (of ownership)". The user of a metaphor alters the reference of the word, "carrying" it from one semantic "realm" to another. The new meaning of the word might be derived from an analogy between the two semantic realms, but also from other reasons such as the distortion of the semantic realm - for example in sarcasm.

Psychologist Julian Jaynes coined the terms 'metaphrand' and 'metaphier', plus two new concepts, 'paraphrand' and 'paraphier'. 'Metaphrand' is equivalent to the metaphor-theory terms 'tenor', 'target', and 'ground'. 'Metaphier' is equivalent to the metaphor-theory terms 'vehicle', 'figure', and 'source'. In a simple metaphor, an obvious attribute of the metaphier exactly characterizes the metaphrand (e.g. the ship plowed the seas). With an inexact metaphor, however, a metaphier might have associated attributes or nuances – its paraphiers – that enrich the metaphor because they "project back" to the metaphrand, potentially creating new ideas – the paraphrands – associated thereafter with the metaphrand or even leading to a new metaphor. For example, in the metaphor "Pat is a tornado", the metaphrand is "Pat", the metaphier is "tornado". As metaphier, "tornado" carries paraphiers such as power, storm and wind, counterclockwise motion, and danger, threat, destruction, etc. The metaphoric meaning of "tornado" is inexact: one might understand that 'Pat is powerfully destructive' through the paraphrand of physical and emotional destruction; another person might understand the metaphor as 'Pat can spin out of control'. In the latter case, the paraphier of 'spinning motion' has become the paraphrand 'psychological spin', suggesting an entirely new metaphor for emotional unpredictability, a possibly apt description for a human being hardly applicable to a tornado. Based on his analysis, Jaynes claims that metaphors not only enhance description, but "increase enormously our powers of perception...and our understanding of [the world], and literally create new objects".