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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.)

Mechanical snail
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Ankur Banerjee
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  • 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 03 '11 at 08:25
  • 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 03 '11 at 08:37
  • 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 03:04
  • @Ankur What about tanh? – timur Mar 24 '11 at 13:11
  • @timur 't-han'. Like tan, but expelling air after the 't'. – Ankur Banerjee Mar 24 '11 at 16:34
  • Well, pronunciations of shortened forms don't depend on those of originals: for instance, prof vs professor. The pronunciation of "Cos" falls in the CLOTH lexical set: so pick the appropriate vowel for CLOTH in your dialect. – RainDoctor Aug 23 '12 at 07:31
  • @timur: I've heard sinh, cosh, and tanh pronounced sinsh, cosh and tansh (I'm not sure whether the consonant at the end of sinh and tanh is sh or ch, but they sound nearly the same in AmE; this is the same phenomenon—epenthesis—that makes prince sound like prints). – Peter Shor Aug 23 '12 at 13:34

4 Answers4

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

Billy ONeal
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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 03 '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 05 '11 at 11:36
  • Yes, even when written "cos", pronounce "cosine". – GEdgar Jul 11 '11 at 13:50
  • And you pronounce "log" as "logarithm"? – David Richerby Feb 19 '14 at 21:41
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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 01:21
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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 01:22
  • @BillyONeal Do you use these much? I work with log(arithm)s pretty frequently and it'd be a real drag to say "natural logarithm of x" however many times a day. (In my case, the base of the log is usually either implied by the context or just plain doesn't matter, so I can usually just say "log" for any logarithm without ambiguity.) – David Richerby Feb 20 '14 at 09:05
  • @DavidRicherby I would say "natural log" or simply "ln" (pronouncing the letters individually) because everyone whom I'd say that to would understand. – Skeleton Bow Mar 05 '17 at 18:02
  • @SkeletonBow I certainly wouldn't say "ell en", since then both "the logarithm of x" and "L times n times x" would be pronounced "ell en ex". – David Richerby Mar 05 '17 at 18:06
  • That's true, but most of the time my audience would understand that I was talking about the natural logarithm from context. Where it could be ambiguous, however, I would definitely say "natural log." – Skeleton Bow Mar 05 '17 at 18:15
  • I have a degree in Maths from an English University and years teaching Maths in school. We would almost always abbreviate in speech, except for sine. We would say log for any type of log provided it was clear which in the context but it was almost always natural in maths. They use logs base 10 in chemistry (e.g. pH). Mathematicians largely gave up logs base 10 when calculators were invented and we stopped using log tables for doing calculations. The pronunciation of sinh etc. was discussed and it was agreed that any valid attempt (including all the ones mentioned here) was OK. – David Robinson Oct 25 '18 at 23:35
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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.

bye
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    +1 American here, and I've only ever heard this version [koʊs, kəʊs]. – Jon Purdy Mar 03 '11 at 08:24
  • 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 machine -- it was configured for Chinese and Hebrew originally, and I haven't been able to exorcise all of the weirdness yet). – bye Mar 03 '11 at 08:38
  • 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 03 '11 at 08:40
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In England everybody I know pronounces this so that it rhymes with "because".

Nicolas Wu
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  • This is what I found at my university (Surrey) too. – Ankur Banerjee Mar 03 '11 at 08:59
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    Or like Bill Cosby :) – Benjol Mar 03 '11 at 09:14
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    There are other slightly alien words where UK English naturalises an 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 03 '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 03 '11 at 14:03
  • @Benjol The vowels in Cosby and because don’t sound at all alike. – tchrist Jun 13 '14 at 03:20
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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! – Simd Apr 01 '15 at 12:48
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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.

joe_young
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  • 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