1. A narrow opening, hole, groove, or channel, especially one for receiving coins in a machine. 2. A position or time when something can take place: Visitors can book a slot a week in advance.

3. An authorization to take off or land at an airport on a specific day during a specified time period: Air traffic controllers assign slots to planes to manage the flow of aircraft in busy airspace, preventing repeated delays that occur when too many planes attempt to fly at the same time.

4. A computer hardware feature for accepting expansion cards: A motherboard may include slots for an ISA, PCI, or AGP card. See also expansion slot and memory slot.

5. A game in which players try to match symbols, either by inserting cash or, in ticket-in, ticket-out machines, a paper ticket with a barcode: The player activates the slot by pushing a lever or button (either physical or on a touchscreen), which causes the reels to spin and stop to rearrange the symbols. When the symbols match, the player earns credits based on a paytable. Most slot games have a theme, with classic symbols such as fruit, bells, and stylized lucky sevens.

Some people who play slot machines are called lurkers, because they spend time watching a machine and then jump in after a long losing streak, hoping that the jackpot will be large enough to offset their losses. However, there is no proof that a machine will pay out soon simply because it has had a long losing streak; the percentage paybacks on different types of machines—video poker, video blackjack, or slot machines—vary widely.