[问题]how to use dictionary to find out whether a noun word has a plural?

pipehappyUID: 159167

I have a webster dictionary and it add "pl" to indicate a noun has a different plural form. But the question is that how I can tell one word can have a plural form.

gdhdannyUID: 125843

When there is a 'pl' after the word, it means the plural form of it has the same spelling as its single counterpart. So if there isn't any 'pl' following the word you are looking for reference, you could easily add a 's' or 'es' in accordance to the ordinary method to deal with the plural transformation.