I'd like to help you out but I am unclear about your question.
What do you mean by "pertain"?
caudal
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.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "is" is "are."
The plural form of "was" is "were."
The plural form of "I" is "we."