1. A previously submitted order to purchase or sell a security that is canceled before it has been executed on an exchange.
2. An order that can't be executed due to parameter limitations, such as a limit order that can't be filled because the price has moved outside of range.
Most equity orders (especially market orders) are executed so fast today that canceling them before execution may not be possible despite the investor's efforts. Limit orders that are outside of the current stock price can usually be canceled online or by calling the broker directly. Other order types that can quickly become canceled orders are "all-or-none" orders and "fill or kill" orders.