Re: A language change question (longish)

pois is invariable, so it has one form for the singular and plural, like
deer
un pois, des pois
a pea, some peas
a deer, some deer

Engl. (old) pease / modern pea ~peas < Fr. pois (sg., i think)


so this is an exapample of misinterpreting an invariable noun as a plural,
or was it borowwed as a plural? Is there a way to tell if a word was
originally borrowed as a singular or plural form after so much time has gone
by?

mabye the change happens whenever a change in the pluralization scheme of
the language changes, and people don't remember that the word was a plural.
I can't think of a case to back that up though.