The English word “slot” dates back to the late 14c., when it referred to a hollow at the base of the throat, above the breastbone. It is a variant of the French word esclot, of uncertain origin. An Old Norse word, slod, is also a close synonym. It is used in the modern sense as a noun; for example, a slot in a newspaper is occupied by the chief copy editor. The first recorded use of the word is in the 1520s, while its definition as a machine dates from 1888.

The basic principle behind a slot machine is that players can be rewarded by winning if their symbols line up. A pay table will show which symbols result in a certain amount of credits. Although some symbols can represent several other symbols, a win can be quite large if they line up in a winning pattern. Most slot machines will display their pay tables on their face; older machines will have them above or below the reels, while newer ones will usually be listed in the help menu.

There are various ways to map different words to a specific slot. For example, an entity value like “New York” can have synonyms such as “Big Apple” or “NYC.” The Dialog Engine will understand that the user means to map NYC to New York when they type NYC. If the user wants to add more synonyms, they can select the text field next to the name and press Enter. When they are finished, they can delete the word from the list by hovering over the synonym and clicking the X.