Most often, "ordinary" is an adjective, so it does not change when it modifies plural nouns. It is correct to say both "an ordinary meal" and "ordinary bananas".
There are some special senses (e.g., civil law and heraldry) in which "ordinary" is a noun. The plural of the noun "ordinary" is "ordinaries".
No, the noun ordinary is a singular noun, a word for a thing that is commonplace. The word ordinary is also an adjective.
The plural of hemisphere is the ordinary S form hemispheres.
The plural form for the demonstrative pronoun this is these.
The plural form of the word inferno is infernos.
The plural form is ranches.
There is no plural word for if.
There is no plural form for the word, countries. This word itself is a plural.
The plural form is data.
The plural form of the word "baby" is "babies."
The plural form for the word 'pioneer' is pioneers.
The plural form of the word "pharynx" is "pharynges."
The plural form of vow is vows.