What is the term for a common expression or colloquialism that is inaccurate or misleading, such as the use of "mental math" to mean "mental calculation" or "mental arithmetic"?

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    Can you give another example because 'mental math' sounds perfectly fine to me. – Mitch Oct 1 '13 at 23:16
  • @Mitch: Let's take that as a feature: the expression can be widely used and acceptable to many. – orome Oct 2 '13 at 11:59
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    No I'm asking for a term that acts like 'mental math' does for you but is different, because I don't understand how 'mental math' is misleading. Can you give another example of a term that is misleading? – Mitch Oct 2 '13 at 12:02

I think you are looking for the word metonymy: a figure of speech in which a thing or concept is called not by its own name but rather by the name of something associated in meaning with that thing or concept.

It is closely related to the more general term synecdoche.

Edit: Now I've read your comments I like the answer of user49727 (catachresis) and think that one is best suited to your demands (the negative connotation). You might also consider faulty generalization and to lump together.

  • So: "'mental math'" is a common metonym for 'mental arithmetic'"? I'd like to be sure to capture the connotation of possible misleading or damage (as, in this example, a popular confusion about the nature and scope of mathematics is perpetuated). – orome Oct 1 '13 at 17:25
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    @raxacoricofallapatorius How is math perpetuating confusion here? Does it not involve calculation and is it also not known as arithmetic? The usage is idiomatic, which would make metonymy correct. – Giambattista Oct 1 '13 at 17:36
  • @JohnQPublic: No. – orome Oct 1 '13 at 17:39
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    What is the difference between math and arithmetic and how does math not involve calculation? Even if you don't accept that, it's idiomatic. Idioms are not always rooted in logic and usually aren't remotely literal. There is no confusion at all because you understand exactly what it means. And arithmetic is basic math. – Giambattista Oct 1 '13 at 17:42

This should come under the rhetorical device called catachresis. Etymologically catachresis (from Greek kata- implying perversion) embodies the sense of misuse (and hence of misleading) you require.

misuse or strained use of words, as in a mixed metaphor, occurring either in error or for rhetorical effect.

  • That's good (but it ruined "...take arms against a sea of troubles..." for me forever!). – orome Oct 1 '13 at 17:40
  • Lol - very true. One of the few inelegant Shakespearisms. – user49727 Oct 1 '13 at 18:03


With "appropriate" meaning "to attribute to a cause or meaning", in this case.

To misappropriate a term means to use it in the wrong way/with the wrong meaning.

  • So could one say that "'mental math'" is a common misappropriation for 'mental arithmetic'"? – orome Oct 1 '13 at 17:20
  • Exactly how I would phrase it. – Zibbobz Oct 1 '13 at 17:23
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    In the US they are synonyms. If you're talking about BrE, that may not be the case. There is no such thing as should not be accepted in the English language. English has no central language authority and standard English is language that is accepted by the majority of educated speakers. If the majority accept it, it's standard. Again, idioms are not to be taken literally, and I would call this idiomatic. – Giambattista Oct 1 '13 at 17:40
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    There is definitely such a thing as misappropriating terms to mean something else though, and regardless of whether or not they are 'accepted', rax is looking for a term that describes this. Individual use aside. – Zibbobz Oct 1 '13 at 17:44
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    @Zibbobz I did not say that misappropriation does not ever occur. But there is no such thing as should not be in English. That assertion is false. Idioms are not misappropriations anyway. – Giambattista Oct 1 '13 at 17:46

Consider malapropism

the use of an incorrect word in place of a word with a similar sound, resulting in a nonsensical, often humorous utterance.

An example is Yogi Berra's statement: Texas has a lot of electrical votes (rather than electoral votes).

The term derives from the French mal à propos meaning inappropriate and was used as the name of a character, Mrs. Malaprop, in an 18th century play.

An alternative term is a Dogberryism from Officer Dogberry in Shakespeare's Much Ado about Nothing.


Misnomer - "a wrong or inaccurate name or designation"

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