1.NounAppropriate, required, reasonable care or carefulness.
"Consumers are required to use their credit cards with due diligence, which includes making sure that strangers cannot find or see their PIN.; You are required to exercise due diligence by immediately reporting unauthorized withdrawals from your account and unauthorized use of your credit card."
2.NounA process during which a potential party to a contract evaluates the assets and liabilities of one or more other potential parties, to assess whether it should enter into the contract.