I am from a non-English speaking country. Should we say monotonous function or monotonic function?

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    $\begingroup$ Monotonic, definitely. Monotone is also fine. Monotonous in everyday usage means boring. $\endgroup$ Apr 12, 2015 at 13:53
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    $\begingroup$ So I guess nobody will be interested in monotonous functions. ;-) $\endgroup$
    – celtschk
    Apr 12, 2015 at 15:24
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    $\begingroup$ In Italian the difference is even worse. The difference is between the correct monotòne and monòtone. (0 letters difference, just the accent). $\endgroup$
    – Bakuriu
    Apr 12, 2015 at 16:57
  • $\begingroup$ Just for completeness, see: math.stackexchange.com/questions/365717/… Apparently, the difference between monotonous and monotonic in some languages is minimal, and we see it often misused as "monotonous" here. $\endgroup$ Nov 6, 2015 at 17:10

3 Answers 3


"Monotonic" or "monotone", but not "monotonous" (boring).


That would be monotonic function. Monotonic is always used in relation to the function you are talking about.


Monotonic describes something this is unchanged or altered, such as the function in maths whereas Monotonous describes something lacking in variety and is usually used in reference to tone.

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    $\begingroup$ "Monotone" is also acceptable (though not mentioned in the question). $\endgroup$ Apr 12, 2015 at 18:42

monotonic for sure is to be used. Monotonic functions are those functions which are either increasing or decreasing. They are such that for each specific value of x there is a unique y(value of function) which does not repeat for any other x.


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