I am looking for a term that describes an acronym that has two possible expansions, but both expansions refer to the same thing. The term "double acronym" doesn't appear to be widely used and is confusing. Some examples:

In human-computer interaction, there is a single tool called CPM-GOMS, where the CPM stands for both "cognitive, perceptual, motor" and "critical path method".

Additionally, a popular cognitive modeling tool called ACT has both "Atomic Components of Thought" and "Adaptive Character of Thought" as its meanings.

In both cases, these are not two distinct tools that coincidentally share the same acronym. They are acronyms that purposefully have two distinct expansions that refer to the same tool.

The usage might also apply to companies who have changed the words in their acronym while keeping the original initialism, such as:

  • Marvel's SHIELD
  • the programming language PHP
  • the chain store TCBY
  • the college exam SAT

However in these cases one expansion is clearly non-standard. There are also unofficial acronyms, such as DVD, which appears to be used equally as "digital video disc" and "digital versatile disc", despite that neither is standard.

It may also apply to translations in which the initialism is preserved, such as the car company BMW which stands for Bayerische Motoren Werke AG, but is often written as Bavarian Motor Works.

There is no wikipedia for "double acronym" and < 6,500 google results for the same search term. Is there a standard term for this usage that I am not aware of? If not, what short phrasing could be best used to describe this usage? Note I am primarily interested in a phrase that captures the first usage (e.g. CPM and ACT).

  • 2
    "ambiguous" doesn't work for you?
    – Mitch
    Jan 12, 2013 at 22:34
  • @Mitch no, i wouldn't say the acronym is ambiguous. it definitively has two expansions that refer to the same thing.
    – Jeff
    Jan 12, 2013 at 22:35
  • 1
    "double acronym" doesn't lead one to think of what you are asking about. You're saying two identical acronyms (same letter sequence), that are abbreviations of two different sets of words, but in the end they still refer to the same thing? I don't think there's a single word for such a thing. It's hard enough to explain. Sure it happens, but a few words is not a problem.
    – Mitch
    Jan 12, 2013 at 22:39
  • 2
    ambiguous means "open to more than one interpretation". Jan 12, 2013 at 22:39
  • 2
    Do you mean like when I read this and said to myself, WTF? (what the frag) ;-)
    – Jim
    Jan 13, 2013 at 1:57

3 Answers 3


This doesn't happen often enough for there to be a single word, or even a standard phrase.

However, as Mitch suggested, ambiguous means:

open to more than one interpretation; not having one obvious meaning

Therefore ambiguous acronym is a good match.

However, remember an acronym is usually an initialism or abbreviation pronounced as a word, like NASA, radar, laser and ACT, unlike BBC and CPM.

So ambiguous abbreviation is a more general term.

  • I'm not looking for a single word necessarily, that tag was added by someone else. Ambiguous is a good suggestion, but to me that connotes, e.g., an acronym used by two organizations for different purposes. thanks for the 'abbreviation' tip
    – Jeff
    Jan 13, 2013 at 19:53
  • 1
    Yes, ambiguous could also mean the same abbreviation is used for two or more different things (eg HMI for Her Majesty's Inspector, Heavy Metal Ions, Himalayan Mountaineering Institute and Hrvatske Matice Iseljenika), but, well, ambiguous is ambiguous like that! You may have to be more explicit, and perhaps introduce any term the first time you use it.
    – Hugo
    Jan 13, 2013 at 21:14

I know this is old, but I came here looking for the same thing.

The best I've come up with is 'dual acronym'.

dual: consisting of two parts, elements, or aspects. The two aspects here being the two expansions that have the same underlying meaning.

'Double acronym' seems to connote two expansions that have different meanings, at least to me.


Is Equivocation ("to call by the same name") closer to your intention? I'd agree that ambiguous perhaps doesn't have the correct connotation of "intentionality" that you are after.

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