With regards to collective nouns, a collective noun is a noun which is singular in form but plural in meaning correct?

For example poultry is a collective, but what about nouns which are plural in form but singular in meaning, such as mathematics are they also considered collective nouns?
"Politics," "the news," "mathmatics" aren't collective nouns.
No. Collective nouns are nouns that refer to a group but are (sometimes) treated as a single unit, like family, committee and team.

Poultry is an unmarked invariable plural noun, like people, police and cattle. They are always plural, though they have no plural ending.

Subjects like mathematics, economics, statistics are among the invariable singular nouns that happen to end in '-s'. Another in this subgrooup is news.