Prediction Market Glossary 2026: 50 Essential Terms Explained

Engaging in prediction market trading requires familiarity with terminology spanning blockchain infrastructure, quantitative methods, and financial markets. This comprehensive glossary presents 64 critical definitions that every prediction market participant must grasp — encompassing execution mechanics, statistical frameworks, and distributed ledger concepts.

Core Trading Terms

Ask (Offer): The minimum price threshold at which a seller agrees to part with shares. When you initiate a market purchase, you transact at this ask level.
Bid: The maximum price at which a prospective buyer commits to acquiring shares. Selling at market rates means accepting the prevailing bid.
Bid-Ask Spread: The gap separating the lowest ask from the highest bid. Narrower spreads indicate deeper liquidity and reduced transaction friction.
CLOB (Central Limit Order Book): The matching engine powering Polymarket and PolyGram infrastructure. This system pairs pending buy orders against sell orders according to price precedence and temporal sequence.
Conditional Token: An on-chain asset representing a binary YES or NO position within a prediction market framework. These tokens reside within smart contracts deployed on Polygon.
Fill Price: The precise rate at which your transaction completed. This may diverge from your quoted expectation if market conditions shift between submission and settlement.
FOK (Fill or Kill): An execution instruction requiring immediate complete fulfillment or automatic cancellation. Fractional execution is prohibited under this directive.
Liquidity: The capacity to transact substantial volumes while maintaining stable pricing. Markets exhibiting elevated participation and compressed spreads demonstrate superior liquidity characteristics.
Market Order: A directive to transact at prevailing market rates instantaneously. While guaranteeing swift execution, the final price remains subject to current market conditions.
Limit Order: A directive specifying a price threshold — execution occurs exclusively at that level or more favorably. The order persists in the book until matched or withdrawn.
Open Interest: The aggregate notional value of all unresolved market positions. Elevated open interest signals robust participation and enhanced market depth.
Slippage: The variance between anticipated execution price and actual settlement price, typically stemming from constrained liquidity at the intended price point.

Probability & Statistics Terms

Brier Score: A quantitative assessment of forecasting precision. Computation involves the mean squared deviation between estimated probability and realized outcome (either 0 or 1), with diminished scores indicating superior performance.
Calibration: The alignment between stated confidence levels and empirical frequency of accurate predictions. Properly calibrated forecasters achieve outcomes matching their stated probabilities — assertions made with 70 % confidence materialize 70 % of the time.
Expected Value (EV): The probabilistically-weighted average return across all conceivable scenarios. Positions exhibiting positive EV represent mathematically advantageous wagers over extended timeframes.
Kelly Criterion: A mathematical framework governing position magnitude optimization: f = (bp - q) / b, wherein b represents net odds, p denotes probability, and q equals 1-p.
Superforecaster: An individual demonstrating sustained superior calibration performance across numerous predictions, consistent with frameworks established through Philip Tetlock's academic investigations.

Blockchain & Settlement Terms

Polygon: The secondary blockchain layer facilitating Polymarket and PolyGram operations. This infrastructure delivers transaction expenses below one cent and achieves finality within approximately two seconds.
USDC (USD Coin): The collateralized stablecoin denominating prediction market settlements. Each unit maintains parity with one US dollar, with issuance administered by Circle and reserves held in US government securities.
Smart Contract: Autonomous blockchain-resident programming that manages prediction market capital and orchestrates payout distribution upon market conclusion.
Oracle: An authoritative external information provider furnishing outcome data to blockchain-based contracts. Polymarket leverages UMA's optimistic oracle architecture for market resolution.
Gas: The compensation remitted to Polygon validators for transaction processing. Polygon-based transactions typically incur fees substantially below one cent.

Market Types

Binary Market: A market structure featuring precisely two mutually exclusive outcomes (YES/NO). This remains the predominant prediction market configuration.
Categorical Market: A market permitting multiple distinct outcomes (exemplified by "Which candidate will secure the Republican nomination in 2028?").
Scalar Market: A market where compensation adjusts proportionally to the outcome magnitude (illustrated by "What will the Bitcoin price reach by December 31?").
Conditional Market: A market whose resolution hinges upon satisfaction of a prerequisite condition. The market becomes void if the conditioning event fails to materialize.

FAQ

Where can I learn more prediction market terminology?: PolyGram's API documentation furnishes exhaustive technical definitions. Polymarket's support resources address operational and user-centric terminology.
What is the difference between a prediction market and a futures contract?: Futures instruments maintain dynamic pricing mechanisms reflecting underlying asset valuations. Prediction markets deliver fixed payouts ($0 or $1) contingent upon event materialization.
What does it mean when a market is "resolved YES"?: The underlying event has occurred, resulting in YES share holders receiving $1 per share. NO share holders receive $0. Smart contract mechanisms execute settlement instantaneously.