A narrow notch, groove, or opening, as in a keyway in machinery or a slit for a coin in a vending machine. Also: a position in a series or sequence; a place to put a letter or number in a keyboard; the act of slotting something.
A machine that pays out credits based on the symbols it displays when activated by a lever or button (either physical or virtual, depending on the type of machine). The payouts are determined by a pay table and vary among machines. Most slots have a theme, and the symbols and bonus features are designed to match it.
In football, the slot receiver is a position that is beginning to replace fullbacks in teams that play a more spread offense. The advantage of using a slot receiver is that they are faster and can run routes in space, while being protected from linebackers.
In programming, a slot is a normal member function that can accept signals, as well as send them. When connecting a signal to a slot, the compiler ensures that the number of arguments in the signal matches the number of arguments passed to the slot. This makes slots a powerful component programming mechanism.