KEY TAKEAWAYS
Slot machines have a vocabulary that mixes mechanical history with modern software: reels, paylines and hoppers sit beside random number generators, volatility and ticket-in, ticket-out. This glossary defines 26 slot machine terms in plain language, each with an example of how a player or casino employee might use it. It is written for readers who are new to the casino floor, who play slots online and want the vocabulary, or who have read a machine’s help screen and still have questions. The terms are grouped into four sets: reels and paylines, bonus features and jackpots, the math behind the machine, and the floor, cabinet and club vocabulary. Definitions are neutral and descriptive; they explain how machines are described, not how to beat them. Rules and names differ between manufacturers and jurisdictions, so where a term varies the entry says so. A quick-reference table closes the entries.
Reels, Paylines and Symbols
These terms describe how a slot spin is laid out and read.
Reel
Definition: A column of symbols that spins and stops to form the result of a spin. Traditional machines have physical reels; video slots show virtual reels on a screen. Three and five reels are common.
Example: “The first reel stopped on a bell, then the second.”
The number of reels and symbols per reel varies by game.
Payline
Definition: A line across the reels on which matching symbols must land to win. Older machines often had one payline through the middle; video slots can have many, including diagonal and zigzag lines.
Example: “The game has 20 paylines, so only symbols on those lines count.”
Only symbols on an active payline pay under the traditional pay-line rule.
Ways to win
Definition: A game layout in which winning symbols pay when they appear on adjacent reels from left to right, with no fixed paylines. The game states how many ways exist, such as 243 on five reels with three rows.
Example: “It’s a 243 ways game, so I don’t pick paylines.”
Sometimes called all ways or any way pays.
Paytable
Definition: The schedule showing which symbol combinations pay and how much each pays for the bet size. On video slots it is usually opened with a button; on older machines it is printed on the glass.
Example: “Check the paytable to see what three scatters award.”
Also written pay table. The help screen explains special features too.
Wild symbol
Definition: A symbol that substitutes for other symbols to complete a winning combination. Many games exclude scatters or bonus symbols from substitution, and some wilds expand or carry multipliers.
Example: “A wild on reel three completed the line.”
Rules for what a wild can replace are stated in each game’s help screen.
Scatter symbol
Definition: A symbol that pays or triggers a feature wherever it lands, without needing to sit on a payline. The glossary of the National Indian Gaming Commission describes scatter pay as paying for a symbol anywhere in the window.
Example: “Three scatters anywhere triggered the bonus.”
In many games scatters are the usual trigger for free spins.
Multiplier
Definition: A value that increases a win by a set factor, such as 2x or 5x. On older machines the word also described a pay schedule in which prizes scaled evenly with the number of coins bet.
Example: “The free spins have a 3x multiplier on every win.”
Modern games apply multipliers to individual wins, to features, or to progressively growing totals.
Bonus Features and Jackpots
Most modern slots add features that interrupt the base game, and some pay jackpots that grow over time.
Free spins
Definition: A bonus feature that awards a set number of spins at no extra cost, usually triggered by a particular combination such as three scatters. Prizes won during free spins are paid at the end of the feature or as they land.
Example: “Landing three scatters awarded ten free spins.”
Free spins in a game’s feature are different from free-spin offers in promotions, which come with separate terms.
Bonus round
Definition: A separate game or screen triggered from the base game, such as a pick-and-win or a wheel. Results come from the game’s own rules and may be played for fixed or random prizes.
Example: “The bonus round was a pick-a-prize screen.”
Not every bonus round involves player choice; some are decided entirely by the game.
Cascading reels
Definition: A feature in which winning symbols disappear and new symbols drop into the empty spaces, which can create further wins from a single paid spin. Also called tumbling reels or avalanche in some games.
Example: “The cascade chained four wins from one spin.”
Name and detail vary by manufacturer.
Jackpot
Definition: The highest prize a machine can pay, or the top prize in any gambling game. It may be a fixed amount stated on the machine, or a progressive amount that rises as bets are placed.
Example: “The top jackpot on this machine is 5,000 coins.”
In everyday talk, a jackpot is any large win; the machine’s rules define the official top prize.
Progressive jackpot
Definition: A jackpot that grows as bets are made. It can be linked to one machine or to a group of machines, and a group-linked progressive usually grows far faster and pays more than any single machine could.
Example: “The progressive meter above the bank is up to 48,000.”
The NIGC glossary distinguishes individual and multiple-machine progressives. A displayed meter shows the current prize.
Hand pay
Definition: A payout made by an attendant or at the cage rather than by the machine itself. It occurs when a win exceeds a preset limit, and in the United States that limit is often tied to the point at which the operator must begin to deduct tax.
Example: “They flagged it for a hand pay because it was over the limit.”
Can also happen after a short pay, when a machine cannot pay out the whole amount.
The Math Behind the Machine
These terms describe how machines decide results and how their payouts are measured over time.
Random number generator
Definition: The software that selects each spin’s result. Modern machines run a pseudo-random number generator constantly, and the number it holds when a player presses spin decides the outcome. It is often shortened to RNG.
Example: “The RNG decided the result the moment I hit spin.”
Because each spin is independent, past results do not affect the next one.
Payback percentage
Definition: The share of the money wagered on a machine that it returns to players over a very long run, typically many thousands of spins. It is also called return to player or RTP, and it applies to total play, not to any one player.
Example: “The help screen lists the payback percentage.”
The NIGC glossary notes that the figure applies to all money played through the machine, not the money you personally put in.
Hit frequency
Definition: How often a machine produces a winning combination, relative to the number of spins played. A high hit frequency does not mean a high payback, because many hits can be smaller than the bet.
Example: “It hits often, but the wins are small.”
Also called hit rate. It is a separate measure from payback.
Volatility
Definition: A measure of how widely results swing around the average. High-volatility slots tend to pay larger wins less often; low-volatility slots tend to pay smaller wins more often. Also called variance.
Example: “It’s a high-volatility game, so the bankroll swings a lot.”
Volatility is a description of the payout pattern, not a promise about any single session.
Hold percentage
Definition: The share of money wagered that a machine or the casino keeps as revenue over time. It is the mirror image of the payback percentage: a payback of 92% corresponds to a hold of 8%.
Example: “Management tracks hold by bank of machines.”
Used mostly by casino operators; players usually see payback instead.
Pay cycle
Definition: A belief that a machine follows a cycle in which it must pay out after a losing stretch to meet its payback percentage. Machines do not work this way, because each spin is decided independently by the random number generator.
Example: “He kept playing because the machine was due to hit.”
The NIGC glossary notes that payback percentages work out over thousands of plays.
Loose slot
Definition: A machine described as paying out well, usually because it is thought to have a higher payback setting. Players generally cannot tell whether a given machine is loose from a few spins.
Example: “They advertise loose slots near the entrance.”
A claim about looseness is only meaningful over a large number of plays.
Floor, Cabinet and Club Terms
These terms cover the credits, tickets and programs players meet at the machine itself.
Ticket in, ticket out
Definition: A cashless system that uses printed vouchers instead of coins. A player inserts cash or a ticket, plays from the credit balance and prints a ticket for the remaining credits, which can be used in another machine or redeemed at a cashier. Shortened to TITO.
Example: “I cashed out and the machine printed a TITO ticket.”
Policies for ticket expiry and redemption vary by casino and jurisdiction.
Denomination
Definition: The value of one credit on a machine, such as one cent, a nickel, a quarter or a dollar. It is not the same as the bet, because many games let a player wager several credits per spin.
Example: “It’s a penny denomination, but the bet is 50 credits.”
The stake is the denomination times the credits wagered.
Max bet
Definition: The most that can be wagered on a single spin, expressed in credits or money. Some features or jackpots are only available when the player wagers the maximum.
Example: “The top prize needs a max bet.”
Read the machine’s rules to see whether a feature depends on bet size.
Slot club
Definition: A casino loyalty program for slot players. A player inserts a card that records time and money played and earns points or rewards in return. Benefits and earning rates differ by casino.
Example: “She earns slot club points every time she plays.”
Also called a player’s club. Rewards are not a change to how the machine pays.
Slot tournament
Definition: An event in which players compete for set prizes on specially configured machines, scoring points from credits accumulated in a limited time or number of spins. Entry rules and prizes are set by the casino.
Example: “The slot tournament starts at noon and runs for an hour.”
Results depend on points scored in the event, not on how much money a player wagers.
Credit
Definition: A unit of value on the machine’s meter. Money inserted becomes credits, wagers are made in credits and wins are added as credits before the player cashes out.
Example: “The meter shows 400 credits left.”
Credit value depends on the machine’s denomination.
Quick-Reference Table of Slot Machine Terms
Scan every term defined above in the table below, then jump to the full entry for the example and notes.
| Term | Short definition |
|---|---|
| Reel | Spinning column of symbols |
| Payline | Line where matching symbols must land |
| Ways to win | Pays on adjacent reels with no fixed lines |
| Paytable | Schedule of winning combinations and prizes |
| Wild symbol | Symbol that substitutes to make wins |
| Scatter symbol | Symbol that pays anywhere on the screen |
| Multiplier | Factor applied to increase a win |
| Free spins | Bonus spins awarded at no extra cost |
| Bonus round | Special game triggered from the base game |
| Cascading reels | Winning symbols vanish and new ones fall in |
| Jackpot | Machine’s top prize |
| Progressive jackpot | Jackpot that grows with every bet |
| Hand pay | Win paid by staff, not the machine |
| Random number generator | Software that picks each spin result |
| Payback percentage | Share of wagers returned over the long run |
| Hit frequency | How often a spin wins |
| Volatility | How widely results swing |
| Hold percentage | Share of wagers the casino keeps |
| Pay cycle | Belief that a machine is due to pay |
| Loose slot | Machine said to have a higher payback |
| Ticket in, ticket out | Voucher system replacing coins |
| Denomination | Money value of one credit |
| Max bet | Largest wager allowed on one spin |
| Slot club | Loyalty program for slot players |
| Slot tournament | Competition for prizes on set machines |
| Credit | Unit of balance shown on the machine |
Related Glossaries
Other casino vocabulary appears in Blackjack Terms: 24 Definitions With Examples and Craps Terms and Slang: 30 Definitions With Examples. The probability behind payback and hit frequency is covered in Gambling Probability Terms: 28 Definitions, and shorthand such as RTP and RNG is collected in Gambling Acronyms and Abbreviations: 24 Definitions.
Frequently Asked Questions
