What is the correct pronunciation for the mathematical abbreviation 'cos' when it is not pronounced in its complete form 'cosine'? I pronounce it as 'k-aw-ss', but a couple of Canadian friends I have pronounce it as 'k-oh-s' (like the adjective 'close'). I tried looking up dictionaries but none that I came across list the IPA / phonetic pronunciation for the mathematical abbreviation.

(I think the former is the British English pronunciation, and the latter is the American English / Canadian English pronunciation.)

  • Another way of putting what my Canadian friends are pronouncing the term as would be 'cosine' with the 'ine' chopped off, as Stan Rogers mentioned in his answer below. – Ankur Banerjee Mar 3 '11 at 8:25
  • Another (possibly) interesting variation in pronunciation - for 'sinh' (hyperbolic sine, I pronounce it like 'shine' while my Canadian friends pronounce it like 'cinch'. And so on for other hyperbolic maths abbreviations. This one is documented in the OED. – Ankur Banerjee Mar 3 '11 at 8:37
  • I like cinch for sinh, and kosh for cosh. By the way, how do you pronounce tan? Tangent or tangens? In Russian, it is tangens. – timur Mar 18 '11 at 15:08
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    @timur In its abbreviated form, I pronounce tan just like that - as in 'sun tan'. Otherwise, I pronounce it as 'tangent'. – Ankur Banerjee Mar 24 '11 at 3:04
  • @Ankur What about tanh? – timur Mar 24 '11 at 13:11

In England everybody I know pronounces this so that it rhymes with "because".

  • This is what I found at my university (Surrey) too. – Ankur Banerjee Mar 3 '11 at 8:59
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    Or like Bill Cosby :) – Benjol Mar 3 '11 at 9:14
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    There are other slightly alien words where UK English naturalises an <o> to /ɒ/ (as in UK 'cot') but N.Am English prefers an /oʊ/ (as in 'coat'). Examples that occur to me are 'kudos' and other Greek words in '-os', but I'm sure there are others with a different final consonant. – Colin Fine Mar 3 '11 at 12:55
  • @Colin I think your comment comes quite close to the answer I was looking for; as in, the origin of the different pronunciations. – Ankur Banerjee Mar 3 '11 at 14:03
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    But how do you pronounce 'because'? The 'au' can be like the 'o' in 'pot' or the 'ou' in cousin or 'or' as in 'born', @tchrist They do to me! – dorothy Apr 1 '15 at 12:48

In speaking, I'd never use either of those pronunciations. "cos" means "cosine" -- say "cosine". Therefore I'd pronounce it "co-sign" ;)

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    It's like asking how to pronounce "Mr". It's pronouced as the word it is, even if it is shortened. – thursdaysgeek Mar 3 '11 at 23:35
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    'Mr' was originally the abbreviation for Magister or Master (rather like Dr). It's now its own word, with irregular pronunciation. – Tim Lymington Jul 5 '11 at 11:36
  • Yes, even when written "cos", pronounce "cosine". – GEdgar Jul 11 '11 at 13:50
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    @David: Yes. Although that is more likely to be pronounced as an abbreviation because 1. log is just a word, so an unambiguous pronunciation exists for it, and 2. it shortens 4 syllables to 1, whereas cosine to cos at most shortens 2 syllables to 1. – Billy ONeal Feb 20 '14 at 1:21
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    @David: And while we're at it yes, I would pronounce "ln" as "natural logarithm" – Billy ONeal Feb 20 '14 at 1:22

Well, I'm Canadian, and I was always taught (and taught, myself, when I was teaching) what would be rendered koʊs in the IPA (hard c, long o, hard s) -- exactly like "cosine" with the "ine" left off.

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    +1 American here, and I've only ever heard this version [koʊs, kəʊs]. – Jon Purdy Mar 3 '11 at 8:24
  • Thanks -- I just noticed I missed pasting in the upside-down omega dealie (obviously, I have all of these glyphs on tap, but I can't get at them directly on this <expressive glyphs missing> machine -- it was configured for Chinese and Hebrew originally, and I haven't been able to exorcise all of the weirdness yet). – bye Mar 3 '11 at 8:38
  • I added a comment to the question on the difference in pronunciation of hyperbolic trig abbreviations. Maybe there's a similar difference for cos? – Ankur Banerjee Mar 3 '11 at 8:40

For what it's worth, my maths teacher says cos like coz with a 'z' sound at the end, as opposed to cosine which he says co, long o, sine as in sign (s-i-y-n).

N.B. tan is just as is sounds, with the 'a' short.

  • On those rare occasions when I needed to refer to hyperbolic functions, I would pronounce "sinh" as "sin-huh", "tanh" as "tan-huh" and "cosh" to rhyme with "posh" or "gosh". (The "-huh" would be more like blowing air out the nose than a pronounced word.) I would also refer to a natural logarithm as "linn"....and sometimes a factorial (e.g., n!) as "N", loud and emphasized. But these were all facetious; I would normally use the full names: hyperbolic [function], natural log[arithm], factorial, etc. – tautophile May 28 '18 at 15:43

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