82ad790e_and_Merchant_Services_Glossary__Definition
[Term] Pre-Auth [Definition] 
Also called an authorization hold, pre-authorization occurs when the cardholder’s bank immediately authorizes a credit card transaction but holds the funds as unavailable from the merchant until he or she officially clears (settles) the transaction. This allows for changes in the sale amount that might occur between the time of authorization and settlement, as in hotel stays where last-minute phone calls or room service use could affect the amount of the final bill after checkout.
Credit Card Processing and Merchant Services Glossary
Definition