The noun form 'cut' is singular; the plural form is 'cuts'.
analysis itself is a singular form
The noun genius is the singular form, the plural form is geniuses.
The singular possessive form of criterion is criterion's
Yes, apple is the singular; the plural form is apples.
Addendum is the singular form; the plural form is addenda, although there is some acceptance for addendums as the plural.
The singular form of the demonstrative pronoun 'these' is this.
The singular form of "that" is "it."
it is already in its singular form.
The singular form is cuff.
"Stratum" is the singular form of stratum. The plural form is "strata".
The form hypothesis is the singular form. The plural form is hypotheses.
A singular form of dice is a die
The singular form of feet is foot.
The singular form of Oases is, Oasis.
The singular form of chromosomes is a chromatid.
"Wash" is the singular form of "wash."
The singular form of diagnoses is diagnosis.