The singular form of vortex is "vortex" and the plural form is "vortices."
Vortex already is a singular form. The plural can be vortexes or vortices. Both are equally correct.
The plural form of vortex is vortices.
The noun quantum is the singular form; the plural is quanta.
"Nucleus" is a singular noun. The plural form is "nuclei".
Pulleys is the plural form; the singular is pulley.
Vortex already is a singular form. The plural can be vortexes or vortices. Both are equally correct.
The plural form of vortex is vortices.
It is singular. The plural is ellipses.
"Is" is the singular form of the verb "to be," used with singular subjects. "Are" is the plural form used with plural subjects.
Vita is singular. The plural form of vita is vitae
This is singular. These is the plural form.
'These' is the plural form of 'this'.
The singular form is Dennis. The plural form is Dennises.
The singular noun is mass. The plural form is masses.
The noun quantum is the singular form; the plural is quanta.
The plural form of a singular woman is women.
The plural of "she" is "they", so the plural of "she had" is "they had".