| Word | Description |
| Card Not Present Account | A merchant account that is established for businesses where credit cards are primarily accepted by phone, mail, or over the Internet and therefore are "not present." Sometimes known as a Mail Order/Telephone Order (MOTO), or E-commerce account. |
| Chargeback | When a consumer contests a purchase that appears on his/her banking statement and they charge it back to the merchant. |
| Checkout Process URL: | The URL for the shopping cart handler that processes the transaction results for a payment. an unmodified zencart installation this would be [base URL]/index.php?main_page=checkout_process. Or [base URL]/catalog/checkout_process.php for oscommerce. |
| CID | Cardholder Identification Data. CID is the American Express term for the 4-digit security code on the front of the credit card. For Visa and MasterCard, it is 3-digits and located on the back. |
| Clearing | The process whereby financial institutions collect or pay out for items drawn on, or paid into, accounts in their institution. E-xact Transactions settles according to the credit card companies' agreements with banking institutions. |
| Client Library | A client library allows you to make API calls from any website and makes it easy to create Ajax applications. Since the library does not require any server-side code on the merchant's server, a payment page can be created and hosted on any web site that serves static HTML. |
| COM | Component Object Model. COM makes it easier to create components (pieces of code) or use preexisting components that can interact with other components and applications (using the object model). A big advantage is that these components can be written using a variety of computer languages. |
| CTR | Customer Transaction Record. With E-xact's Transaction Processing Solution, the CTR is issued upon completion of a transaction. It states the business name, has an authorization number, and lists all important transaction details. |
| CVC2 | Card Validation Code 2. CVC2 is the MasterCard term for the 3-digit security code on the back of the credit card (Visa and MasterCard). For American Express, it is 4-digits and located on the front. |
| CVD | Cardholder Verification Data. CVD is a 3-digit security code on the back of the credit card (Visa and MasterCard). For American Express, it is 4-digits and located on the front. Also known as CVV, CVV2 (Visa), CID (American Express), and CVC2 (MasterCard). |
| CVV | Cardholder Verification Value a 3 or 4 digit security code on the back of the credit card (Visa and MasterCard). For American Express, it is 4-digits and located on the front. |
| CVV2 | Cardholder Verification Value2. CVV2 is the Visa term for the a 3-digit security code on the back of the credit card (Visa and MasterCard). For American Express, it is 4-digits and located on the front. |