I'd like to help you out but I am unclear about your question.
What do you mean by "pertain"?
caudal
Tails
The plural form for the noun tail is tails.
The plural possessive form for the tails of the foxes is the foxes' tails.
A lizard's tail. Five lizards' tails.
Flagellum (flagella is the plural form)
Flagella. Flagella Flagellum (flagella is the plural form) flagella
The plural form of mouse is mice.
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
It has no plural form.