k-means clustering is a scientific and technical term.

Wikipedia and some books use "k-means clustering" instead of "K-Means Clustering", while some other posts use "K-Means Clustering".

Is there a rule to capitalize a canonical name, a scientific and technical term?

  • There are certain broad conventions for capitalization, like capitalizing the first word of a sentence and each important word in a title or proper noun; however, there is no ultimately authority. You must ask your editor, publication, or organization for guidance, or in the absence of a house style, adopt a style manual appropriate to your audience and tastes and be consistent in its application.
    – choster
    Commented Jun 17, 2019 at 15:42
  • Don't confuse a title with a phrase.
    – Lambie
    Commented Jan 21, 2022 at 19:09

2 Answers 2


Neither means nor clustering is a proper noun, so they should be capitalized only in a title (if such capitalization is customary in the context; in Wikipedia it is not).

The k appears to be a conventional symbol for a number that is important to the subject matter, and these (the most famous example may be c for the speed of light) do not change their case even in titles. I would avoid beginning a sentence with this k.


If there is an official statement that a certain term should be spelled in a certain way, that definition should be used. E.g. iPod should not be spelled IpOd.

Optionally, if there is no official rule, and if the author is known, you may use the spelling used by the author, as a token of respect for his contribution.

Optionally, you may use the "most usual way" of spelling it, whatever that means.

Actually, if there is no official way of spelling, you can use anything which makes sense.

Practical exception: if some authority mandates a certain spelling, you should probably use that spelling, even if you do not agree, IF it can harm you to do otherwise.

Example: if your university mandates you to spell the iPod as IpOd, then use IpOd - just to be use you did not waste X years of efforts for nothing.

  • Writers (and editors and typesetters) do not necessarily need to use the presentation preferred by a person or institution. The writer's goal is to inform the reader, and using unfamiliar and non-standard capitalization is distracting and hurts readability— a disservice to everyone except the marketing department. AP allowing iPod mid-sentence is one thing; insisting upon adidas and REALTOR® is another.
    – choster
    Commented Jun 17, 2019 at 15:48

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