The word 'duo' is the singular form; the plural form is duos.
The singular form of "duo" is "duet".
The singular form of the word "criteria" is "criterion."
The singular form of the word "señores" is "señor."
The singular form of Sioux is "Sioux." It is both the singular and plural form of the word.
The word hypopharynx (one word) is the singular form; the plural forms are hypopharynges or hypopharynxes.
The singular form of "stratum" is "stratum." The word does not change in its singular form.
Duo? otherwise, duet...
The noun 'duo' is a singular noun, a word for one group of two people or things (a pair).The plural noun is 'duos' a word for two or more groups of two people or things.
The noun 'duo' is singular; a singing performance by two singers, a word for two people who perform together, work together as a team, or who regularly do things together. The plural form is duos. Example sentence:Batman and Robin are known as the dynamic duo.
The singular form of the word flagella is flagellum.
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 of the word "criteria" is "criterion."
The singular form of "genera" is "genus".