Yes, this is a very pedantic question! Is the musical instrument called the triangle badly named? The instrument in question has three sides, but only two angles. Might the name tricosta or triparte be more appropriate?

In some languages the name of the geometric shape for which the instrument is named does in fact mean "three sides" as opposed to "three angles", such as Hebrew (משולש). Therefore the name is in fact appropriate in these languages. This question only refers to the English name of the instrument, without consideration for translations, etymology, or use in other languages.

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    In Russian, the instrument is called (музыкальный) треугольник, which literally means (musical) triANGLE. The same is in Armenian, եռանկյունի, which also means three ANGLES. So English is not unique in this sense Jul 18, 2012 at 16:06
  • Thank you Mahnax. I find this question constructive as I am not an expert in the English language. I would like to solicit the opinion of experts in the field regarding borderline cases such as this. The goal is not to change the name of the instrument.
    – dotancohen
    Jul 18, 2012 at 16:11
  • Why the downvote? Downvoter, please explain so that I might improve the question. I don't care about the rep, but I do care about keeping the E.SE site full of quality questions. Thanks.
    – dotancohen
    Jul 18, 2012 at 16:18
  • @JasperLoy: Yes, but the part removed is one of the angles! So it is now a biangle.
    – dotancohen
    Jul 18, 2012 at 16:20
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    @dotancohen the third angle is implied. The instrument wouldn't vibrate as well without the missing part. Jul 18, 2012 at 16:23

1 Answer 1


It is dangerous to assume that an English word means the same thing as its two component parts! It can be a helpful tool to discern the meaning of new words, but try not to rely on it. Context clues are way more important.

In English, the word "triangle" means a closed polygon with three sides. As such, it is an appropriate name for the instrument.

  • Three sides, or three angles? A closed polygon having either property would ensure the other, but this assurance is not guaranteed as we use the word for other similar devices (such as the musical instrument in question). As noted in the OP, the instrument is not a closed polygon so the name might not be appropriate.
    – dotancohen
    Jul 18, 2012 at 16:17

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