Should we prefer singular or plural in tags?

Question

Likewise many sites of StackExchange family (and even the very StackOverflow), we should decide the unified style for tags.

Should we prefer singular or plural in tags, in cases where both would make sense?

For example:

• noun vs. nouns
• іменник vs. іменники

Answer 1

At first I thought that simply plural was the answer, but it seems like in order to follow the conventions of other sites we might need a more complicated rule.

For example, whole other sites have a "nouns" tag instead of just "noun", they don't have an "orthographies" tag, the have an "orthography" tag.

My best attempt at describing this rule would be to say that whichever number sounds like the best fit in this sentence:

I have a question about ________

or in Ukrainian:

________ є предметом мого питання

Answer 2

My own preference is —

Plural

because:

• This seems to be a mainstream;
• Other sites like Wikipedia often use plural for categories;

Answer 3

I'd say we should decide different cases individually:

• parts of speech — I'd say plural;
• synonym (also antonym, homonym) — I'd say plural;
• other future cases — to decide.

Why I vote for plural for parts of speech and for synonym/antonym/homonym:

• as in ELL;
• as in English.

_{Though argument about category names Wikipedia doesn't works fully, because (say) for parts of speech}:

• _{English Wikipedia uses plural (Verbs);}
• _{Russian Wikipedia uses mix (Глагол‎, Числительные);}
• _{Ukrainian Wikipedia uses singular (Дієслово‎).}

_{(Still, Russian and Ukrainian Wikipedias might just not normalized it yet, as they're smaller than English and can't pay attention to every category name.)}