Encyclopedia of Roulette: Key Terms and Definitions
A plain-language glossary of the terms used across this site and in roulette analysis generally. Definitions are neutral and link to deeper guides where it helps.
- 29 key terms
- Neutral definitions
- Links to full guides
This roulette encyclopedia defines the terms you will meet in roulette analysis - from American roulette and bankroll to variance, risk of ruin and Voisins du Zéro. Each entry is a concise, neutral definition, with links to deeper guides where useful. Use it as a quick reference while reading the system and strategy pages.
Roulette terms A to Z
American roulette
A 38-pocket wheel with both 0 and 00, giving a 5.26% house edge. Read more →
Biased wheels
Physical imperfections that make some numbers hit more often; extremely rare on modern, maintained equipment.
Bankroll
The total money set aside for play. Sound bankroll management is the core of roulette risk control. Read more →
Clocking
Recording past results in the hope of spotting patterns. Spins are independent, so clocking has no predictive value.
Cold numbers
Numbers that have not appeared recently. They are no less likely to hit next - a common gambler's-fallacy trap.
Column bet
An outside bet on one of three vertical columns of 12 numbers, paying 2:1. Read more →
Dozen bet
An outside bet on 1-12, 13-24 or 25-36, paying 2:1. Read more →
D'Alembert
A negative progression that adds one unit after a loss and removes one after a win. Read more →
European roulette
A 37-pocket wheel with a single zero and a 2.70% house edge. Read more →
Expected value
The average result of a bet over many repetitions; always negative in standard roulette. Read more →
Flat betting
Staking the same amount every spin - the lowest-variance approach and the benchmark for other systems. Read more →
French roulette
A single-zero wheel with player-friendly rules such as La Partage, lowering the even-money edge. Read more →
House edge
The casino's built-in mathematical advantage: 2.70% European, 5.26% American, ~1.35% French even-money. Read more →
Inside bets
Bets on the numbers themselves - straight up, split, street, corner, six line - paying more and winning rarely. Read more →
La Partage
A French rule returning half an even-money stake when zero lands, roughly halving the edge on those bets. Read more →
Labouchère
A cancellation system that uses a number line as a profit target, crossing entries off on wins. Read more →
Martingale
A negative progression that doubles the bet after each loss to recover in a single win. Read more →
Neighbours
Numbers physically adjacent on the wheel; the basis of neighbour and sector bets. Read more →
Outside bets
Bets on large groups - red/black, odd/even, high/low, dozens, columns - paying less and winning more often. Read more →
Paroli
A positive progression that doubles the bet after each win, usually for a set number of wins. Read more →
Payout
The amount returned on a winning bet, quoted 'to 1' - for example 35:1 on a straight up. Read more →
Progression
Any system that changes the stake based on previous results; positive (after wins) or negative (after losses). Read more →
Risk of ruin
The probability of losing your entire bankroll. It rises sharply with steep progressions and large units. Read more →
Standard deviation
A measure of how far results spread from the average; high for inside bets, low for even-money.
Table limits
The minimum and maximum bet allowed. The maximum caps progressions and is where Martingale breaks. Read more →
Variance
The natural swing of short-term results around the long-term average; the reason sessions feel lucky or unlucky. Read more →
Voisins du Zéro
'Neighbours of zero' - a called sector covering 17 numbers around the zero on the wheel. Read more →
Wheel sectors
Groups of numbers defined by their position on the wheel, used for coverage bets. Read more →
Zero
The green pocket that creates the house edge on even-money bets; American wheels add a second, 00. Read more →
Frequently Asked Questions
The casino's built-in advantage: 2.70% on European, 5.26% on American and about 1.35% on French La Partage even-money bets.
The probability of losing your entire bankroll. It rises steeply with aggressive progressions and large unit sizes.
Variance is the swing of results around the average; standard deviation is its square root, a common measure of that spread.
No. Each spin is independent, so a number that has not appeared recently is no more likely to come up next.
Called bets covering groups of numbers by their position on the wheel - Voisins du Zero covers 17 numbers around the zero.