Day Order
Any order to buy or sell a security that automatically expires if not executed on the day the order is placed.
Investopedia Commentary
A day order will not be executed if the limit or stop order prices were not met during the day. A way to increase the life of an order is to order securities on a 'good 'till cancelled' basis, where, as the name implies, the trade will not expire until it is cancelled or until it reaches a maximum time limit set by the brokerage.
Related Links
The Basics Of Order Entry
See also: Good 'till Cancelled, Limit Order, Order, Stop Order
day order