Learn English – the proper plural of “a series”?


In math, we use the term series a lot, and there are many types of series.

How should I craft my sentence when I have three different ones in mind to talk about? Should I settle down for a less mortal alternative of “list of series” or something like that?

The existing question on The possessive and plural forms of “series” suggests the usage of series’. But is that all?

If that’s the only solution, then could you please explain the usage of apostrophe symbol at the end? Is that a plural marker or a possessive marker, or both?

Best Answer

Series (like deer, salmon, and sheep) is pronounced and spelled the same in the plural as in the singular. If either the singular or the plural is used as a possessive, an apostrophe is added to show that in print, though there is no pronunciation difference in speech. Thus,

  • The series doesn't converge. (singular)
  • The series don't converge. (plural)
  • This series' limit is unknown. (singular possessive)
  • These series' limits are unknown. (plural possessive)

More examples can be seen here.

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