Glossary - Polymarket US Documentation

Market Structure & Hierarchy

Term	Definition
Category	Broadest classification level organizing instruments by event type (e.g., Sports, Politics, Crypto, Culture).
Series	More specific classification within a category, such as a sports league or topic (e.g., NFL, NBA, US Presidential, Bitcoin).
Event	A specific occurrence with multiple possible outcomes. Each event consists of one or more instruments representing the complete set of tradable outcomes.
Product	The type of contract structure used to format instruments (e.g., Athletic Event Contract, Election Winner Contract, Total Score Contract).
Instrument	The tradable symbol representing a specific outcome for an event. Follows consistent naming conventions for easy identification. Also called a market.
Market	Same as an instrument. A tradable outcome with defined resolution criteria and sources.
Contract	An instance of an instrument. You trade contracts in quantities (e.g., buying 100 contracts). Each contract settles at $1.00 if the outcome occurs and $0.00 if it does not.

Trading Basics

Term	Definition
Long position	Buying contracts of an instrument, trading on the outcome occurring. You pay the current price per contract and receive $1.00 per contract if the outcome happens.
Short position	Selling (shorting) contracts of an instrument, trading on the outcome not occurring. You receive the current price per contract but must cover potential losses if the outcome happens.
Order	A request to buy or sell contracts at a chosen price.
Order book	List of bids and asks showing available prices and size at each level.
Bid	Highest price buyers are willing to pay.
Ask	Lowest price sellers are willing to accept.
BBO (Best Bid and Offer)	The best bid and ask prices currently available in the order book - the tightest spread at the top of the book.
Spread	Gap between the bid and the ask.
Size	Number of contracts available to buy or sell at a given price.
Liquidity	How much size is available to trade at listed prices.

Order Execution

Term	Definition
Fill	When your order completes, fully or partially.
Partial fill	When only part of your order fills.
Execution price	The price at which your order fills.
Fill price	Average price you receive when your order fills across multiple levels.
Marketable limit order	An order that fills at the best available price shown on your screen.
Price impact	How much your fill price changes because of limited liquidity.
Slippage	Difference between expected and actual execution price.
Maker	Trader who adds liquidity by placing an order on the book.
Taker	Trader who removes liquidity by filling an existing order.

Positions & Account

Term	Definition
Open position	Contracts you currently hold.
Closed position	A position you no longer hold because you sold it or the market resolved.
Position value	Real-time dollar value of your open positions.
Cash balance	Funds in your account not tied to open positions.
Buying power	Cash available to open new positions after margin is applied.
Instant buying power	Part of your deposit that becomes available to trade immediately.
Margin	Funds locked to cover the maximum possible loss of a short position. Equal to $1.00 per contract shorted.
Max gain	The most you can earn on a position.
Max loss	The most you can lose on a position.

Market Lifecycle

Term	Definition
Clarification	Extra context added to explain how rules should be understood.
Resolution	When Polymarket determines the final outcome of a market using the sources listed in the rules.
Settlement	Final payout of $1.00 for winning contracts and $0.00 for losing contracts.

Fees & Display

Term	Definition
Fees	Trading or platform fees applied to executed orders.
Odds display	How prices are shown, such as price, percent chance, or American odds.
Open order	An order waiting on the book to be filled.
Order status	Whether an order is open, filled, or partially filled.
History	Section showing your past filled orders and closed positions.

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