In general terms, a catachresis is a mistake in language. For most cases, it involves using a word in the wrong context or straining the word's meaning from its norm. Mixed metaphors are one prominent example of catachresis. Individuals might engage in misapplication of a word unintentionally, or they might misuse the word on purpose in order to create a stylistic or rhetorical effect. The use of catchresis usually separates a word from its literal meaning, so it is a figure of speech.
A cathachresis might change the meaning of a word. When the change results from unintentionally replacing one word's meaning with another word's meaning, a malapropism has taken place. This usually happens when two words sound similar, such as using the word "electrical" in a sentence rather than the word "electoral." An intentional change might be used as a literary tool, a means of making a point or as an expression of extreme emotion. If an individual references a slithering politician, for example, the term "slither" is understood as more of a commentary on the politician's reptilian personality than a literal reference to sliding over a surface.
One of the most prominent examples of a catachresis is the mixed metaphor, and this figure of speech occurs when an individual is seeking to make an exaggerated and illogical comparison between two objects. In other words, two objects are being compared that have no obvious similarities. Mixed metaphors are often used intentionally in literary works as creative and unique ways of expressing particular ideas. In William Shakespeare's famous play Hamlet, one of Hamlet's most renowned speech includes a catachresis of this variety: "... to take arms against a sea of troubles ... ." For this comparison, the writer has forged a connection between two seemingly unrelated topics: war and the ocean.
Intentional catachresis is particularly prominent in postructuralist works. This literary philosophy thrives on ambiguity and breaking down traditional literary techniques, structures and meanings. As such, postructuralist authors embraced the wordplay and confusion that is inherent in catachresis. Therefore, catachresis abounds in such works. Sounds might be seen rather than heard, darkness might be bright, or an individual might experience a dull sharpness.
On occasion, the catachresis might create a word or reference that previously did not exist, and in these cases, it fills a void in meaning. For example, some words are grammatically incorrect but are so pervasive in use that they become an unofficial part of a language. The English word "ain't" is such an example, and it is referred to as a solecism. Words also might arise to describe a previously unnamed action that has become commonplace in popular culture. In the computing world, for example, the word "tweet" has become recognized as a reference to messages created on the social network called Twitter.