Wikipedia:Naming conventions (pluralization)

Convention: In general only create page titles that are in the singular, unless that term is always in a plural form in English (such as economics).

Let's say you were writing a page about crayons. Should you call the page [[crayons]], which is basically what the page is about, or [[crayon]], which makes it easier to link to from passages like "Harold took out his purple crayon and drew up the covers" Probably the latter. One can still write [[crayon]]s (which the software is smart enough to render as crayons), but if the page is called [[crayons]], then whenever one wants to use the term in the singular, one is forced into typing the ungainly [[crayons|crayon]]. (If you didn't understand the latter link, you need to read this: How does one edit a page)

An exception to this rule affects the articles titled Legendre polynomials, Chebyshev polynomials, Hermite polynomials, etc. An article about John, Paul, George, and Ringo would not be titled "Beatle", nor would one expect to find "Joint Chief of Staff" as a title. Although one does refer in some contexts to "a Chebyshev polynomial" or "the nth Chebyshev polynomial", generally such a polynomial is of interest only because it is part of the polynomial sequence called the Chebyshev polynomials, the sequence being thought of for most purposes as a unit.