A thin opening or groove in something. Examples include a mail slot in a mailbox or a groove on a door. Also, a position or role that someone fills.

In a conventional central processing unit, the term slot refers to the operation issue and data path machinery surrounding a functional unit (FU). Modern conventional CPUs usually have several compute pipelines, such as two arithmetic logic units and one floating point unit. Each of these pipelines can only execute one instruction per basic instruction cycle. If a pipeline has more instructions in process than that, it cannot be issued to again in the next basic cycle. This state is referred to as having multiple slots.

The Refilled Slots field on the Program Information Profile displays a 1 only if all PT stipended and Ed Award Only slots are filled, or if type II third term FT members exit with less than 15% of their slot hours completed.