A notch or narrow opening, such as a keyway in a piece of machinery or the slit for a coin in a vending machine. Also: a position in a group, series, or sequence. [from Middle English slitt, from Proto-Germanic *sleutana, related to lock, castle]
A slot is a specific game design that includes the number of reels, symbols on those reels, bonus rounds, and other features that are unique to the game. The slot also defines the RTP (Return to Player) rate and variance (how much and how often a slots pays out) for that particular game. It’s important to look at these numbers and features when choosing which slot to play. A higher RTP means a better chance of winning, but high volatility can mean more frequent small wins or long dry spells.