A company sell ads for my newspaper and also bill the advertisers.
From every ad check  they take 20 per cent and at the end of the month
they  gives my company 80 per cent of all monies received. Is it fraud
or embezzelemt if they deposit the checks but withold the payment from
me longer than a month while telling me that they are still waiting
for the money to come in?

Read your contract.

And even if it does not raise to the level of fraud, you may still
have a cause of action against them for breach of contract.

-This is not legal advice and should not be relied upon as such.