Terms and glossary

Xavi Torrez iGaming analyst & Roulette specialist

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Last updated: April 17, 2026

Every roulette term you will encounter at a table or in a strategy guide — explained clearly and completely. This glossary covers bet types, wheel mechanics, French terminology, special rules, and casino procedures. Use the alphabet navigation to jump directly to any term, or read through from the beginning to build a complete vocabulary before your first session.

A

American Roulette

The version of roulette most commonly found in casinos across North, Central, and South America. The wheel has 38 pockets: numbers 1 through 36, a zero (0), and a double zero (00). The extra pocket raises the house edge from 2.70% (European) to 5.26%. Payouts are identical to the European wheel, making the American version mathematically inferior for players. Full guide: American Roulette.

Announced Bets

Bets where the player declares the bet verbally and then immediately places the chips on the table. Distinguished from true call bets (where chips are placed after the spin). Announced bets are standard practice on European and French tables. The most common are Voisins du Zéro, Tiers du Cylindre, and Orphelins — all of which cover specific sections of the physical wheel. See also: Call Bet, French Bets, Racetrack.

B

Biased Wheel

A roulette wheel on which manufacturing imperfections, wear, or damage cause certain numbers to land more frequently than probability predicts. Historic cases of players exploiting biased wheels — most famously Joseph Jagger at Monte Carlo in 1873 — involved tracking thousands of spins to identify statistical anomalies. Modern wheels are precision-engineered and regularly tested, making exploitable bias extremely rare in regulated casinos.

Block Betting

A betting strategy that covers a contiguous section of the roulette wheel — a “block” of neighbouring numbers — rather than numbers based on the grid layout. Used in sector-based strategies and announced bets. The Voisins du Zéro is the most prominent example of a block bet.

C

Call Bet

A bet placed verbally — the player calls the bet without immediately placing chips. True call bets are not permitted in most regulated casinos because they create credit risk. Most casinos allow the related announced bet, where the declaration is made verbally but chips must be placed on the table immediately to confirm the wager.

Carr

French roulette terminology for a Corner Bet — a single chip placed at the intersection of four numbers on the betting grid. Pays 8:1. See also: Corner Bet.

Cheval

French roulette terminology for a Split Bet — a chip placed on the line between two adjacent numbers. Pays 17:1. See also: Split Bet.

Column Bet

An outside bet covering one of the three vertical columns of 12 numbers on the betting grid. Placed in the box at the end of the relevant column. Pays 2:1. Win probability on European wheel: 32.43%. Zero is not included in any column — it loses all column bets when it lands. French term: Colonne.

Corner Bet (Square Bet)

An inside bet covering four numbers that form a square on the betting grid. The chip is placed at the centre point where all four numbers meet. Pays 8:1. Win probability: 10.81%. French term: Carr. Example: a chip at the intersection of 1, 2, 4, and 5.

Croupier

The casino employee who manages the roulette table — spinning the wheel, releasing the ball, calling “no more bets,” placing the dolly on the winning number, clearing losing chips, and paying winning bets. “Croupier” is the formal term; “dealer” is also used, particularly in American casinos. In live online roulette, the croupier is a trained professional broadcast via video stream. Full guide: What Is a Croupier?

D

D’Alembert System

A betting system in which you add one unit to your bet after a loss and subtract one unit after a win. The slowest-moving of the common negative progression systems — suitable for long sessions on a limited budget. Does not change the house edge. Full guide: D’Alembert Strategy.

Dolly

The marker the croupier places on the winning number on the betting grid after the ball lands. No chips may be placed, moved, or removed from the table while the dolly is present. The croupier removes it only after all payouts for that round are complete. Touching chips while the dolly is on the table is a serious breach of table etiquette and may result in being asked to leave.

Double Zero (00)

The additional green pocket found only on American roulette wheels, alongside the standard single zero (0). Its presence raises the house edge from 2.70% to 5.26%. Straight-up bets on 00 pay 35:1 — the same as any other number. Full analysis: Double Zero Wheel Guide.

Dozen Bet

An outside bet covering one of three groups of 12 numbers: 1–12 (First Dozen), 13–24 (Second Dozen), or 25–36 (Third Dozen). Pays 2:1. Win probability: 32.43%. Zero is not included — it loses all dozen bets when it lands.

E

En Plein

French roulette terminology for a Straight Up bet — a chip placed directly on a single number. Pays 35:1. See also: Straight Up.

En Prison

A special rule applying to even-money outside bets when zero lands. Rather than losing, the bet is “imprisoned” — locked on the table for one more spin. If the next spin wins, the original stake is returned with no profit. If it loses, the full stake is forfeited. Mathematically equivalent to La Partage — both reduce the house edge on even-money bets from 2.70% to 1.35%. Standard on French Roulette, occasionally on European. See also: La Partage.

Even-Money Bet

Any bet that pays 1:1 — you win the same amount as you staked. The three even-money bets in roulette are Red/Black, Odd/Even, and High/Low. Each covers 18 of the 37 numbers on a European wheel. Win probability: 48.65% (not 50%, because zero is excluded). These bets benefit from La Partage and En Prison rules when available.

European Roulette

The most widely played version of roulette globally. The wheel has 37 pockets — numbers 0 through 36 — with a single green zero. House edge: 2.70%. The standard format at all reputable online casinos and most land-based casinos outside North America. Full guide: European Roulette.

F

Fibonacci System

A betting system using the Fibonacci number sequence (1, 1, 2, 3, 5, 8, 13…). Move one step forward after a loss, two steps back after a win. Less aggressive than Martingale — bets escalate more slowly. Full guide: Fibonacci Strategy.

Five Number Bet

An inside bet exclusive to American Roulette covering 0, 00, 1, 2, and 3. Pays 6:1. The house edge on this bet is 7.89% — the worst single bet in standard roulette and the only bet on any standard wheel that breaks the uniform house edge of that wheel. Never place this bet.

French Bets

Announced bets based on sections of the physical wheel rather than the number grid. A French bet is placed as several individual bets simultaneously to cover all numbers in a wheel sector. The three standard French bets are Voisins du Zéro, Tiers du Cylindre, and Orphelins. Available on European and French wheels via the racetrack interface. See also: Announced Bets, Racetrack.

French Roulette

A single-zero roulette variant using the same 37-pocket wheel as European Roulette. Distinguished by La Partage and En Prison rules (always active) and French terminology on the table layout. The La Partage rule reduces the house edge on even-money bets to 1.35% — the lowest of any standard roulette variant. Full guide: French Roulette.

H

High / Low Bet

An outside even-money bet covering numbers 1–18 (Low) or 19–36 (High). Pays 1:1. Win probability: 48.65%. Zero causes all high/low bets to lose unless La Partage applies.

Hot and Cold Numbers

Numbers displayed on the results board showing which numbers have landed most frequently (hot) or least frequently (cold) over recent spins. Hot and cold numbers have no predictive value — each spin is an independent event and past results do not influence future outcomes. The board is useful for entertainment and for tracking session history, not for identifying “due” numbers. Full guide: Hot and Cold Numbers.

House Edge

The mathematical advantage the casino holds over the player, expressed as a percentage of each bet the casino expects to retain over time. On a European single-zero wheel: 2.70%. On an American double-zero wheel: 5.26%. On a French wheel with La Partage (even-money bets): 1.35%. The house edge applies equally to every bet on a given wheel and cannot be changed by any betting system. Full guide: House Edge Guide.

I

Inside Bets

Bets placed on the number grid itself — on specific numbers or the lines and intersections between them. Cover fewer numbers, win less frequently, and pay more per win. The inside bet types are: Straight Up (1 number, 35:1), Split (2 numbers, 17:1), Street (3 numbers, 11:1), Trio (3 numbers including zero, 11:1), Corner (4 numbers, 8:1), and Six Line (6 numbers, 5:1). Every inside bet carries the same house edge as outside bets on the same wheel. See full payout table: Odds and Payouts.

L

La Partage

“The sharing” in French. A rule that returns half of an even-money outside bet stake automatically when zero lands. Reduces the house edge on even-money bets from 2.70% to 1.35% — the lowest available in standard roulette. Always active on French Roulette; occasionally available on European tables. Mathematically equivalent to En Prison. Full guide: La Partage Rule.

Layout

The felt-covered betting surface of the roulette table, printed with the number grid and outside bet boxes. The layout mirrors the numbers on the wheel and is where all chips are placed. On a French layout, bet labels appear in French (Rouge/Noir, Pair/Impair, Passe/Manque). On European and American layouts, English labels are standard.

Lightning Roulette

A live dealer roulette variant by Evolution Gaming. Before each spin, 1 to 5 numbers are randomly assigned multipliers of 50x to 500x. The base straight-up payout is reduced from 35:1 to 29:1 to fund the multiplier pool. Outside bets pay at standard European rates. Full guide: Lightning Roulette.

M

Martingale System

The most widely known betting system in roulette. Double your bet after every loss; reset to the base unit after every win. A single win recovers all prior losses plus one unit of profit. The system fails when a losing streak hits the table maximum or depletes the bankroll before recovery is possible. Does not change the house edge. Full guide: Martingale Strategy.

Mini Roulette

A compact roulette variant using a 13-pocket wheel (numbers 0 through 12). Payouts are recalculated for 13 pockets — a straight-up bet pays 11:1 rather than 35:1. The base house edge is 7.69%, but many Mini Roulette games include La Partage, reducing it to 3.85% on even-money bets. Full guide: Mini Roulette.

N

Neighbours Bet

A custom announced bet covering a specific number and its two immediate neighbours on each side of the physical wheel — five numbers total, placed as five straight-up bets. Called as “X and the neighbours” or “X neighbours.” Available via the racetrack interface on digital tables. Requires 5 chips per bet.

No Zero Roulette

A rare promotional variant with no zero pocket — 36 numbers only. The theoretical house edge is 0%, but the format is typically offered with reduced payouts or additional fees that restore the casino’s advantage. Full guide: No Zero Roulette.

O

Odds

The probability of a bet winning, expressed as a percentage or ratio. In roulette, odds are fixed by the number of pockets on the wheel. A straight-up bet on a European wheel has 1 in 37 odds of winning (2.70%). “Odds” also refers to the payout ratio — “35 to 1 odds” means the bet pays 35 units for every 1 unit wagered. See our full odds and payouts guide.

Orphelins (Orphans)

A French announced bet covering the 8 numbers on the wheel not included in Voisins du Zéro or Tiers du Cylindre. The numbers are: 1, 6, 9, 14, 17, 20, 31, 34. Requires 5 chips — four placed as splits and one as a straight-up on number 1. Win probability: 21.62%. See also: French Bets.

Outside Bets

Bets placed in the boxes surrounding the number grid — covering large groups of numbers. Pay less per win but win more frequently than inside bets. The outside bet types are: Red/Black (18 numbers, 1:1), Odd/Even (18 numbers, 1:1), Low/High (18 numbers, 1:1), Dozen (12 numbers, 2:1), and Column (12 numbers, 2:1). Zero causes all outside bets to lose unless La Partage or En Prison applies.

P

Paroli System

A positive progression betting system — double your bet after each win, for a maximum of three consecutive wins, then reset. The inverse of Martingale: you escalate bets after wins rather than losses. Maximum loss per cycle is always the base unit. Full guide: Paroli Strategy.

Payout

The amount the casino pays on a winning bet, expressed as a ratio to the stake. A 35:1 payout on a straight-up bet means a €10 bet returns €350 in profit. Payouts in roulette are fixed and standardised — they do not change between sessions or casinos using the same variant. See the complete table: Odds and Payouts.

Pocket

One of the numbered compartments on the roulette wheel in which the ball can land. A European wheel has 37 pockets (0–36). An American wheel has 38 (0, 00, 1–36). Numbered pockets alternate between red and black; zero pockets are always green. The metal dividers between pockets are called frets or separators.

Provably Fair

A cryptographic verification system used in crypto-native online casinos. Before each spin, the casino commits to a server seed hash. After the spin, the seed is revealed — you can independently verify that the result was not manipulated using your client seed and the hash function. Allows player-level verification of every individual spin result rather than relying solely on annual third-party audits. See our crypto roulette guide.

R

Racetrack

An oval diagram of the wheel’s number sequence displayed on digital roulette interfaces. It allows players to place announced and neighbours bets by clicking directly on the wheel sectors, rather than individually placing chips for each component bet. Available on European and French digital tables. Not available on American wheels.

RNG (Random Number Generator)

Software that generates unpredictable results for each spin of a digital roulette game. Certified RNGs are independently audited by testing laboratories such as eCOGRA or iTech Labs to confirm their statistical randomness. A certified RNG produces results equivalent to a fair physical wheel. All reputable online casinos publish their RNG audit certificates. See also: Provably Fair.

RTP (Return to Player)

The percentage of all money wagered that a game returns to players over time. RTP is 100% minus the house edge: European Roulette RTP = 100% − 2.70% = 97.30%. French Roulette with La Partage (even-money bets): 98.65%. American Roulette: 94.74%. A higher RTP means less expected loss per euro wagered.

S

Sixainne

French terminology for a Six Line Bet — a bet on six numbers across two adjacent rows. Pays 5:1. See also: Six Line.

Six Line (Double Street)

An inside bet covering six numbers across two adjacent horizontal rows on the betting grid. The chip is placed at the outer edge where two rows meet. Pays 5:1. Win probability: 16.22%. French term: Sixainne. One of the most commonly used inside bets in combination strategies due to its coverage-to-payout balance.

Split Bet

An inside bet on two adjacent numbers on the betting grid. The chip is placed on the shared line between any two horizontally or vertically adjacent numbers. Pays 17:1. Win probability: 5.41%. French term: Cheval.

Straight Up

An inside bet on a single number. The chip is placed in the centre of any number on the betting grid, including zero. Pays 35:1 — the highest payout on any standard roulette bet. Win probability: 2.70% (1 in 37 on European wheel). French term: En Plein.

Street Bet

An inside bet on three consecutive numbers in a horizontal row. The chip is placed on the outer left or right edge of the row on the betting grid. Pays 11:1. Win probability: 8.11%. There are 12 possible street bets on a European layout, plus Trio bets that incorporate zero. French term: Transversale.

T

Tiers du Cylindre

“Third of the wheel” in French. An announced bet covering 12 numbers on the section of the wheel directly opposite zero — roughly one third of the wheel. Requires 6 chips placed as splits. Win probability: 32.43%. Numbers covered: 5, 8, 10, 11, 13, 16, 23, 24, 27, 30, 33, 36. See also: French Bets, Announced Bets.

Transversale

French roulette terminology for a Street Bet — a chip placed on the outer edge of a three-number horizontal row. Pays 11:1. See also: Street Bet.

Trio Bet

A three-number inside bet that must include zero. Only two combinations are possible: 0-1-2 or 0-2-3. The chip is placed at the intersection of zero and the two adjacent numbers. Pays 11:1. Only available on single-zero (European and French) wheels — not on American wheels due to the different grid layout.

V

Voisins du Zéro

“Neighbours of zero” in French. The largest of the three standard announced bets — covers 17 numbers surrounding zero on the wheel. Requires 9 chips placed across multiple splits, a corner, and a street. Win probability: 45.95%. Numbers covered: 0, 2, 3, 4, 7, 12, 15, 18, 19, 21, 22, 25, 26, 28, 29, 32, 35. See also: French Bets.

W

Wheel Checks

The special unmarked chips used exclusively at a physical roulette table. Each player is assigned a unique colour — the chips have no cash value at any other table in the casino. This colour-coding prevents disputes over which player placed which chip on which number. Wheel checks are exchanged for standard casino chips when you leave the table.

Z

Zero (0)

The green pocket present on all roulette wheels. On European and French wheels, there is only one zero — giving a house edge of 2.70%. On American wheels, a second green pocket (double zero, 00) is added, raising the edge to 5.26%. Zero is not red or black, not odd or even, not high or low — it causes all outside bets to lose unless La Partage or En Prison applies. A straight-up bet on zero pays 35:1.

Zero Spiel

A German announced bet (literally “zero game”) that covers zero and the six numbers closest to it on the wheel: 12, 35, 3, 26, 0, 32, 15. Requires 4 chips. Popular in German casinos and some European live tables. A subset of the Voisins du Zéro, covering only the innermost numbers surrounding zero.