Rating: ⭐⭐⭐⭐⭐
Verdict: A-Z terms every player should know
Last updated: March 2026
The Complete Online Slots Glossary — A to Z
Whether you are new to online slots or a seasoned player, our comprehensive A-Z glossary covers every term you will encounter. Bookmark this page as your definitive reference guide.
A — Autoplay
A feature that allows the slot to spin automatically for a set number of spins without you clicking each time. Most UK casinos limit autoplay options due to UKGC responsible gambling requirements. You can usually set a loss limit and a single win limit to stop autoplay automatically.
B — Bonus Round
A special mini-game triggered within a slot, usually by landing scatter symbols. Bonus rounds can take many forms: free spins, pick-and-click games, wheel spins or special reel modes. They typically offer higher win potential than the base game.
C — Cascading Reels
Also called Avalanche Reels or Tumbling Reels. Winning symbols explode and are replaced by new ones falling from above. If the new symbols form another win, the process repeats, potentially creating chain reactions of consecutive wins from one spin. Used in Gates of Olympus, Gonzo’s Quest and all Megaways slots.
C — Cluster Pays
A win mechanic where matching symbols must form clusters (groups of touching symbols horizontally or vertically) rather than line up on specific paylines. Examples include Aloha! Cluster Pays and Reactoonz.
F — Fixed Jackpot
A jackpot that remains at a set, fixed amount regardless of how much is wagered. Opposite of a progressive jackpot. Fixed jackpots are won by hitting a specific combination of symbols.
F — Free Spins
Spins that cost nothing to play, either triggered in-game by scatter symbols or awarded as a casino bonus. In-game free spins often include special features like sticky wilds or multipliers. Casino free spins bonuses may have wagering requirements.
H — High Variance
See: Volatility. High variance (high volatility) slots pay infrequently but for larger amounts. They require a larger bankroll and patience. Examples: Book of Dead, Dead or Alive 2, Gates of Olympus.
H — Hold and Win
A popular bonus mechanic where special money symbols lock in place while the other reels respin. More money symbols landing during the respins also lock. Continue until you run out of respins or fill all positions. Featured in Wolf Gold, Piggy Riches and many others.
L — Low Variance
Low variance (low volatility) slots pay frequently but in smaller amounts. Ideal for extended play sessions and smaller bankrolls. Examples: Starburst, Twin Spin, Thunderstruck.
M — Megaways
A revolutionary slot mechanic from Big Time Gaming featuring variable numbers of symbols per reel, creating up to 117,649 ways to win. Licensed to dozens of providers. See our Megaways slots guide.
M — Multiplier
A multiplier increases your win by the stated amount. A 5x multiplier on a £10 win pays £50. Multipliers can apply to individual wins, free spins totals or specific symbol values. Cascade slots often feature increasing multipliers during free spins.
P — Pay Both Ways
Wins can be formed from left-to-right AND right-to-left. This doubles the number of possible winning combinations. Featured prominently in Starburst and some other low-variance games.
P — Payline
A set path across the reels where matching symbols must land to form a win. Traditional slots have 9-25 paylines. Modern video slots can have 243, 1,024 or even unlimited paylines (ways to win). Always check the paytable to understand the payline structure. Read our paytable guide.
P — Progressive Jackpot
A jackpot that grows over time as a small percentage of every bet placed is added to the prize pool. Progressive jackpots can reach millions of pounds. Examples: Mega Moolah (world record), Mega Fortune, Hall of Gods.
R — RNG (Random Number Generator)
The certified computer algorithm that ensures every spin result is completely random and independent of all previous spins. All UKGC-licensed slot games use independently certified RNGs. This guarantees fair play and makes it impossible to predict or manipulate results.
R — RTP (Return to Player)
The theoretical percentage of wagered money a slot pays back over millions of spins. An RTP of 96% means the slot returns £96 for every £100 wagered on average. UK players should aim for slots with 95%+ RTP. Read our full RTP guide.
R — Re-spin
A single reel spin triggered by a special symbol or feature, often awarded after a near-miss or wild symbol landing. Different from free spins as only specific reels or the whole set may respin.
S — Scatter Symbol
A special symbol that pays regardless of position on the reels (does not need to be on a payline). Landing 3+ scatters anywhere typically triggers the free spins bonus round. Scatters are often the key to a slot’s bonus feature.
S — Sticky Wilds
Wild symbols that remain in position for one or more subsequent spins, rather than disappearing after a single spin. Featured in Dead or Alive 2 (High Noon Saloon), Jack Hammer and many others. Sticky wilds dramatically increase win potential.
W — Ways to Win
An alternative to fixed paylines where any matching symbols on adjacent reels count as a win, regardless of exact vertical position. 243 ways to win (3×5 grid) and 1,024 ways (4×5 grid) are common formats.
W — Wild Symbol
A special symbol that substitutes for most other symbols to help complete winning combinations, similar to a joker in card games. Types include standard, expanding, sticky, stacked and multiplier wilds. Every modern slot features at least one wild symbol.
FAQ — Online Slots Glossary
What is the most important slot term to understand?
RTP and volatility are the two most important terms for UK players. Together they tell you how much a slot pays back and how it distributes wins. See our volatility vs RTP guide for a full explanation.
What is the difference between paylines and ways to win?
Paylines are fixed paths where symbols must align. Ways to win count any matching adjacent symbols regardless of exact position, creating more potential winning combinations.
What does RNG mean?
Random Number Generator — the certified algorithm that ensures every spin result is completely random and fair.
What is a scatter symbol?
A special symbol that pays or triggers bonuses regardless of position on the reels. Three or more scatters typically activate the free spins bonus round.
What does high variance mean?
High variance (high volatility) means the slot pays out large wins infrequently. Expect long losing stretches punctuated by occasional big wins. Only suitable for players with sufficient bankrolls.
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