Metaphor in the narrow sense is one among the many tropes or figures of speech recognized by traditional rhetoric. The Oxford English Dictionary defines metaphor in this sense as ‘Application of name or descriptive term to an object to which it is not literally applicable (e.g. a glaring error)‘. Other tropes include simile, hyperbole, metonymy and synccdoche. Nowadays, however, it is common to describe almost any non-literal use of words as metaphorical. It is useful to have a general term to contrast with the literal since the problems posed by metaphor in the narrow Sense are shared by many other tropes. The principles behind the traditional classification of tropes are anyway not very clear. (Even a general contrast with the literal might be questioned by those who share Quine’s doubts about the whole notion of meaning.)

The term metaphor is also frequently used in even broader senses, as when an allegory or a picture is described as a metaphor for something. Of course the term metaphor like any other can itself be used metaphorically; so let us agree that literally speaking metaphor is a linguistic phenomenon which only exists where a contrast can be drawn between the literal and metaphorical use of words. While not wishing necessarily to reject other uses of the term, these should be regarded as metaphorical.