The noun 'series' is the plural form of an uncountable (mass) noun.
singular: A series of playoffs took place before the tournament.
plural: He has published three series of adventure novels, each with a different hero.
The plural of series is series
The singular of the word "series" just happens to be "series."
the plural noun of series is the same ,no change
There is no plural form it is just series.
The plural for series remains series. You can have one series, or many series.
Series is both singular and plural.
Series is a noun that has the same form in the singular and the plural. There is no need for an apostrophe, unless it is in the possessive case: series's for the singular possessive and series' for the plural possessive.
The singular form is it, the plural form is they(subjective) and them (objective).
The word crisis is singular. The plural form of crisis is crises.
The singular possessive form is lesson's.
The singular possessive form is grotto's.
Series is a noun that has the same form in the singular and the plural. There is no need for an apostrophe, unless it is in the possessive case: series's for the singular possessive and series' for the plural possessive.
The singular form of the word flagella is flagellum.
The word 'duo' is the singular form; the plural form is duos.
The singular form of "series" is "series." It remains the same whether referring to one or multiple sets of related things.
That is the singular form; the plural form is those.
'Jackhammer' is the singular form.
The singular form is commando.
The word dog is the singular form.
"Biopsy" is the singular form, while "biopsies" is the plural form.
The singular form of the word "possum" is possum. The plural is possums.
The singular form for diagnoses is diagnosis.
The singular form of "genera" is "genus".