The noun relevance is a non-count (mass) noun; relevance is expressed in degrees, for example some relevance, much relevance, no relevance.
The noun 'mice' is the plural form of the singular noun 'mouse'.
The singular noun is "louse" and the plural noun is "lice."
"Book" is a noun that has both a singular and plural form: "book" (singular) and "books" (plural).
"Children" is a plural noun. The singular form is "child."
The noun 'circus' is a singular noun.The plural noun is 'circuses'.
The noun juggler is a singular noun. The plural noun is jugglers.
The singular noun is Tuesday.The plural noun is Tuesdays.
The singular noun is trio; the plural noun is trios.
The noun 'orchid' is a singular noun, a word for one.The plural noun is 'orchids'.
The noun mailbox is the singular form; the plural is mailboxes.
Statistics is plural, the singular form is statistic.
No, Mice is a plural noun. Mouse is the singular noun.