Jumper is singular. The plural is jumpers
The plural form of He has a red jumper is They have red jumpers.
The singular form of feet is foot.
The singular form is hilum.
The form plumber is the singular form; the plural form is plumbers.
The singular form would be majesty.
The singular form of the demonstrative pronoun 'these' is this.
The singular form of "that" is "it."
The singular form is cuff.
it is already in its singular form.
"Stratum" is the singular form of stratum. The plural form is "strata".
The form hypothesis is the singular form. The plural form is hypotheses.
The plural form of He has a red jumper is They have red jumpers.
A singular form of dice is a die
The singular form of feet is foot.
The singular form of Oases is, Oasis.
"Wash" is the singular form of "wash."
The singular form of chromosomes is a chromatid.