Definition of ironclad. 1  1 : sheathed in iron armor âused especially of naval vessels. 2  2 : so firm or secure as to be unbreakable: such asa : binding an ironclad oathb : having no obvious weakness an ironclad case against the defendant.
Best Answer: CR means a credit. If this appears on the balance due line of your statement, it means that you owe nothing and that you are that much ahead of future charges and no payment or acknowledgment is needed.
If you have a CR balance on your credit card, that means that basically they owe YOU money, because your payments and returns were more than your purchases. In that case, no you don't have to pay anything.