According to Webster's New World College Dictionary, 4th edition, the definition of catachresis is the following:
"catachresis (n): incorrect use of a word or words, as by misapplication of terminology or by strained or mixed metaphor" (p. 229)
The roots of the word are (what else?) Greek, from kata, which means "against" or "down," and chresthai, which means "to use."
Other words using the prefix cata in a similar way include cataclysm, catabolism, cataclastic, catacomb, catadromous, and catafalque. (Perhaps some of those will become words of the day later on...)
On a side note, I almost called this blog Catachresis...but decided that naming my blog after something I wish to avoid might not be the wisest of ideas.
9 years ago