Pluralize

Pluralize["noun"] gives the plural form of the English word "noun".

Pluralize["noun",n] gives the inflected form of "noun" for n instances. 

Pluralize[{"singular","plural"},n] inflects using the specified forms.

Pluralize[spec,list] uses the length of list to determine the inflection to use. 

Please visit the official Wolfram Language Reference for more details and examples on core symbols.