An economic model of a market process in which orders are collected into batches of buys and sells and then analyzed to determine a clearing price that will decide the market price. Also referred to as "call market".
The NYSE uses a similar process before the opening bell in order to determine opening prices. A specialist will look at all the collected orders for a particular security and select the price that will clear the greatest number of trades. In fact, up until 1871 all trading on the NYSE was executed in this fashion.