A denomination is a way of classifying things — it names the type or value of something. Denomination often refers to money. For example, $20 bills are of the same denomination.
When denomination is applied to money, you’ll often hear the terms “lower denomination” or “higher denomination.” If you hand the cashier a $50 bill to pay for your latte, she might ask if you have a bill in a lower denomination — she’s asking for a smaller bill, like a $5 or a $10. Denomination can apply to other things that are categorized by type, such as playing cards or groups within the same religious tradition.