ski
The singular form of the word flagella is flagellum.
Criterion is the singular form of criteria.
The word 'duo' is the singular form; the plural form is duos.
No. Apostrophes are almost never used to form a plural.The spelling ski's is a possessive noun, e.g.He has to be careful of his left ski's position on the last turn.His right ski's color is black and his left ski's color is white.
The singular form of the word "señores" is "señor."
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.
The singular possessive form of jury is jury's
The word "biopsies" is the plural form of the word. The singular form is "biopsy."
The singular form of Sioux is "Sioux." It is both the singular and plural form of the word.