Prediction market glossary: 80+ terms

This prediction market glossary gives one-sentence definitions of more than 80 terms used on Polymarket and on Nimb, from spread and open interest to neg-risk markets, pUSD and builder codes. Each entry links to the docs page that explains it in full, with worked examples.

How do you use this glossary?

Terms are listed A–Z. Each has its own anchor, so you can link to one directly, for example /docs/glossary#open-interest. Definitions are one or two sentences; follow "Read more" for the full explanation. Prices are written as chances in %, moves in points and money in $. Wallet, collateral and oracle terms follow Polymarket's documentation at the time of writing; check docs.polymarket.com for changes.

Two pairs people often confuse:

Spread vs depth. The spread is the gap between the best price to buy and the best price to sell; depth is how much money sits in the order book near those prices. A narrow spread with little depth still moves when you trade size. See spread and order book depth.
Volume vs open interest. Volume counts money that changed hands over a period; open interest counts the value of positions still open. See volume and open interest.

A

A reading (Nimb): Nimb's reading of a market is its one-sentence summary: "Traders see a 41% chance…, down 4 points this week." It leads every market panel and every /markets page. Read more
All-in amount: The all-in amount is the dollar figure you type on Nimb's order ticket, which already includes Polymarket's platform fee and Nimb's builder fee. Fees are folded into the number of shares you get, never added on top. Read more
Alpha: In Nimb's docs, alpha means informational edge: something you know or have read in the data that the price does not yet reflect. It is not a promised return, and most apparent edge is noise or fees. Read more
Ask: The ask is the lowest price at which someone in the order book is willing to sell a share right now. If you buy immediately, you pay the ask. Read more

B

Bid: The bid is the highest price at which someone in the order book is willing to buy a share right now. If you sell immediately, you receive the bid. Read more
Break-even probability: The break-even probability is the chance at which a trade neither makes nor loses money once fees are counted. It sits slightly above the price, for example 42.2% on a $100 Yes bought at 41% in a fee-charging market. Read more
Brier score: The Brier score is the average squared gap between forecast probabilities and what happened (1 or 0), so 0 is perfect and 0.25 is what you get by always saying 50%. It is the standard way to grade how accurate a set of market prices was. Read more
Builder code: A builder code is the public identifier an app attaches to every order it sends to Polymarket, so Polymarket can attribute the order and pay the app's builder fee. Orders placed through Nimb carry Nimb's builder code. Read more
Builder fee: A builder fee is a percentage of an order's value that Polymarket collects for the app that sent the order, in addition to Polymarket's own fee. On Nimb it is a small builder fee, included in the price you see. Read more

C

Calibration: Calibration is how closely stated chances match outcomes: a well-calibrated market's 70% outcomes happen about 70% of the time. It is measured over many markets, never from one result. Read more
Category: A category is one of the seven groups Nimb sorts markets into, each with its own colour: Geopolitics (red), Politics (blue), Finance (yellow), Crypto (orange), AI & Tech (green), Sports (khaki), Climate & Culture (purple). Each category gets room on the map in proportion to the money traded on its undecided outcomes, at least 4 markets and at most 40% of the map. Read more
Chance: On Nimb, a chance is a share price read as a percentage: a Yes at $0.41 shows as a 41% chance. See implied probability. Read more
CLOB: CLOB stands for central limit order book, the system Polymarket uses to match buy and sell orders. See order book. Read more
Close-only: Close-only is a restriction under which you can sell or close positions you already hold but cannot open new ones. At the time of writing (2026-11-07), Polymarket applies it in the United States, the United Kingdom, France and about 35 other countries and regions. Read more
Correlation: Correlation (ρ, from −1 to 1) measures how consistently two markets' prices move in the same or opposite direction over the same periods. It shows co-movement, not cause, and on short histories it is often chance. Read more

D

Date ladder: A date ladder is a set of related markets that ask whether the same event happens by successive dates ("by March", "by June", "by December"). Their prices should rise with the date; a later date priced below an earlier one is a sign to look closer. Read more
Deposit Wallet: A Deposit Wallet is the smart-contract account wallet Polymarket creates for your wallet address to hold your pUSD and shares; it stays controlled by your own signer. Polymarket accounts created since May 2026 use it by default. Read more
Depth: Depth is the dollar value of orders resting close to the mid price, on the buy side and the sell side. The more depth, the larger the order you can place before the price moves against you. Read more
Dispute: A dispute is a challenge to a proposed market result, made by posting a bond during the challenge window. A disputed result goes to a new proposal or a vote by UMA token holders, which can delay payout by days. Read more

E

EIP-712: EIP-712 is the Ethereum standard for signing structured data, so your wallet shows what you are approving in readable fields. See signature. Read more
End date: The end date is the date by which a market's question must be decided under its rules. A market can keep trading after its end date until it is resolved, and can resolve early if the event happens first. Read more
Entry → mark: Entry → mark shows a position's average purchase price next to its current market price, for example "38% → 44%". The gap, times the number of shares, is the unrealised P&L. Read more
Event: An event is the real-world question that one or more markets are about, such as an election, with one market per outcome. On Nimb's map, one circle stands for one event. Read more

F

Factor: A factor is a common driver that moves several markets at once, such as Bitcoin's price or interest-rate expectations. Nimb treats factors with caution: 30 days of data rarely prove one. Read more
False positive: A false positive is a link or signal that appears in the data by chance rather than because of a real relationship. Nimb publishes its own estimates: before tightening, 43% of 30-day "moves with / against" links were expected to be false. Read more
Fill: A fill is the part of an order that has been matched with another trader and executed. An order can fill in full, in part, or not at all. Read more

G

Gamma API: The Gamma API is Polymarket's public service for market and event data: titles, outcomes, volumes, liquidity and status. Nimb polls it every minute for volumes. Read more
Gate: A gate is a pass-or-fail test a market must clear before it can appear on Nimb's map: tradable, active enough, not already decided, and with a tradable book (spread at most 4 points or $10k of depth). Read more
Geoblock: A geoblock is Polymarket's location check, which tells an app whether trading is allowed from your country. Nimb calls Polymarket's geoblock endpoint before every order. Read more

H

Hedged position: A hedged position is one where a wallet holds both Yes and No in the same market, so the two sides largely cancel out. Nimb nets these out: a hedged set is not a bet on either side. Read more
Holder: A holder is a wallet that owns shares in a market, shown on Nimb as a grey circle with a line to the market. Nimb lists the largest public holders per side. Read more
Hysteresis: Hysteresis is a rule that makes it harder for a market to leave the map than to enter it, so the map does not flicker as ranks shift. A market enters at one rank and leaves only after falling clearly below it. Nimb does not apply hysteresis at launch. Read more

I

Implied probability: Implied probability is the chance of an outcome that a share price implies: a share paying $1 that trades at $0.41 implies about 41%. It is the crowd's estimate, not a forecast by Nimb. Read more
Informative volume: Informative volume is money traded on outcomes that are still undecided, weighted by how far the price is from 0% or 100%. Nimb ranks markets by it, so heavy trading at 99% counts for little. Read more

L

Last trade: The last trade is the price at which the most recent matched trade happened. In a quiet market it can be stale and differ from the current bid and ask. Read more
Limit order: A limit order is an order to buy or sell at a set price or better, which rests in the order book until someone matches it or you cancel it. It waits for a fill instead of taking the current price. Read more
Liquidity: Liquidity is the money resting in the order book, ready to trade, at or near the current price. The less there is, the more your own order moves the price, and the less reliable prices and exits become. Read more
Long-shot bias: Long-shot bias is the tendency for unlikely outcomes to be priced higher than how often they actually happen, so a 3% outcome may come true less than 3% of the time. It is well documented in betting markets and appears in prediction markets too. Read more

M

Maker: A maker is the trader whose resting limit order is in the book when another order matches it, adding liquidity. On Polymarket, makers do not pay the platform fee. Read more
Market: A market is a single Yes/No question that you can trade, such as "Will X happen by December 31?", with one Yes share and one No share. An event with several outcomes holds one market per outcome. Read more
Market maker: A market maker is a trader who keeps buy and sell orders in the book on both sides to earn the spread, rather than to take a view. Nimb flags likely market makers in holder lists, because their positions say little about the outcome. Read more
Market order: A market order is an order to buy or sell now at the best prices available in the book. It fills straight away but can move the price if the book is thin. Read more
Market reading: Market reading is working out what a prediction market's price, flow and holders say about an event, and how much to trust it. It is the core idea behind Nimb: read the market before you trade it. Read more
Mergeable set: A mergeable set is a matched pair of one Yes and one No share in the same market, which together are always worth $1 and can be merged back into $1 of pUSD. Large mergeable holdings are locked money, not a view on the outcome. Read more
Mid price: The mid price is the halfway point between the best bid and the best ask. Polymarket generally displays it as the market's price, switching to the last trade when the spread is wide. Read more
Money flow: Money flow is the dollar value of Yes bought minus No bought in a market, per hour, by traders who crossed the spread. "$333k more went to No than to Yes over the past week" is a money flow reading. Read more
Moved together / opposite: "Moved together" and "moved opposite" describe two markets whose prices rose and fell at the same times, or in mirror image. See moves with / against. Read more
Moves with / against: Moves with / against is Nimb's list of markets whose prices moved together or opposite to the one you are reading. It shows only on 30D, needs at least 30 joint observations and |ρ| ≥ 0.5, and must survive a leave-one-out test. Read more
Multi-outcome event: A multi-outcome event is an event with more than two possible results, such as an election with many candidates, traded as one Yes/No market per outcome. The outcome prices should add up to about 100%. Read more

N

Neg-risk: Neg-risk (negative risk) is Polymarket's mechanism linking the markets of a multi-outcome event where only one outcome can win. See neg-risk market. Read more
Neg-risk market: A neg-risk market is a market inside a multi-outcome event where exactly one outcome can win, so a No share in one outcome can be converted into a Yes share in every other outcome. This makes positions across the event cheaper to hold and keeps prices consistent. Read more
Net exposure: Net exposure is the number of Yes shares a wallet holds in a market minus its No shares: the part of its position that gains or loses depending on the outcome. A wallet with 1,000 Yes and 900 No has a net exposure of 100 Yes shares. Read more
No share: A No share pays $1 if the outcome does not happen and $0 if it does. Its price is roughly 100% minus the Yes price. Read more

O

Open interest: Open interest is the total value of shares still held in a market, the money currently at stake on its outcome. It rises when new positions open and falls when they close or resolve. Read more
Oracle (UMA): An oracle is the system that tells a blockchain contract what happened in the real world; Polymarket uses UMA's Optimistic Oracle, where a proposed result stands unless someone disputes it. UMA token holders vote on disputed results. Read more
Order book (CLOB): The order book is the live list of all open buy orders (bids) and sell orders (asks) for a share, sorted by price. Polymarket runs a central limit order book (CLOB), and Nimb streams it for live prices. Read more
Outcome: An outcome is one possible result of an event, such as a candidate winning. Each outcome has its own Yes and No shares and its own chance. Read more

P

Platform fee: The platform fee is the fee Polymarket itself charges on taker orders in markets that have one, set per market and largest for prices near 50%. Makers do not pay it, and Nimb includes it in the all-in amount. Read more
Point (pt): A point is one percentage point of chance: a move from 45% to 41% is down 4 points. Nimb reports moves in points, not in percent, to avoid confusion. Read more
POL (gas): POL is the native token of the Polygon network, used to pay transaction fees ("gas"). Polymarket's account wallets handle most trading actions without gas, but moving tokens yourself on Polygon needs a little POL. Read more
Polygon: Polygon is the blockchain network on which Polymarket's shares and collateral live. Your wallet must be set to Polygon to trade. polygon.technology · Read more
Prediction market: A prediction market is a market where people trade shares that pay $1 if an event happens and $0 if it does not, so the share price works as the crowd's estimate of the chance. Polymarket and Kalshi are the largest. Read more
Price: A share's price is what traders currently pay for it, between $0 and $1, which Nimb shows as a chance in %. A price of $0.41 reads as 41%. Read more
pUSD: pUSD is the dollar token Polymarket uses as collateral, an ERC-20 token on Polygon backed by USDC. Deposits of USDC through Polymarket's bridge arrive as pUSD. Read more

R

Read and execute: Read and execute is Nimb's workflow: read the market in the analysis panel, then act on it in the order ticket, in one place. In English we say "from reading to execution". Read more
Realised P&L: Realised P&L is the profit or loss you have locked in by selling shares or by a market resolving. It no longer changes with the price. Read more
Recovery phrase: A recovery phrase is the list of 12 or 24 words that can restore a self-custody wallet, and anyone who has it controls the wallet. Write it down offline and never type it into a website; Nimb will never ask for it. Read more
Redeem: To redeem is to exchange winning shares for $1 each in pUSD after a market resolves. Losing shares are worth $0. Read more
Resolution: Resolution is the process that decides a market's result under its rules and makes winning shares redeemable. On Polymarket it runs through the UMA oracle. Read more
Resolution source: The resolution source is the authority a market's rules name for deciding its result, such as an official election body or a price feed. Read it before trading: the market pays on what the source says, not on what you expect. Read more

S

Selection score: The selection score is the number Nimb uses to rank markets for the map, combining money traded on undecided outcomes, order book depth, the size of the move and whether the market resolves within 7 days. The top 110 per timeframe are shown. Read more
Self-custody wallet: A self-custody wallet is a crypto wallet where only you hold the keys, such as MetaMask or Rabby, so no company can move your funds. It is what you connect to Nimb to trade. Read more
Share: A share is a contract that pays $1 if its outcome happens and $0 if it does not. Every market has Yes shares and No shares. Read more
Signature (EIP-712): A signature is your wallet's cryptographic approval of a message or order; Polymarket orders use EIP-712 typed signatures, so your wallet shows the fields you approve. Signing an order does not cost gas, and Nimb cannot place an order without it. Read more
Slippage: Slippage is the difference between the price you expected and the average price you actually got, caused by your order eating through the order book. It grows with order size and shrinks with depth. Read more
"Smart money": "Smart money" is a popular label for wallets believed to trade well, often used loosely for any large holder. Nimb uses it only in quotes: size is not skill, and a wallet's past results say little about its next trade. Read more
Spread: The spread is the gap between the best bid and the best ask, measured in points. A 4-point spread means buying and selling straight away costs you about 4 points. Read more

T

Taker: A taker is the trader whose order matches an order already resting in the book, taking liquidity. Takers pay Polymarket's platform fee where the market has one. Read more
Taker flow: Taker flow is money flow counted from takers only: the dollars of orders that crossed the spread to buy Yes minus those that bought No. It shows who was in a hurry to trade, and on which side. Read more
Theme: A theme is a labelled group of markets about the same underlying story, such as Bitcoin & ETH or US midterms, drawn on Nimb's map with dashed lines. Dashed lines are themes, never money. Read more
Timeframe: A timeframe is the window of past trading Nimb uses to select, size and describe markets: 1H, 12H, 24H, 3D, 7D or 30D, with the map opening on 7D. Changing it changes circle sizes, moves and, from 24H upwards, which markets are on the map. Read more

U

UMA: UMA is the oracle protocol Polymarket uses to resolve markets. See oracle (UMA). Read more
Unrealised P&L: Unrealised P&L is the profit or loss on shares you still hold, valued at the current market price. It changes with every price move until you sell or the market resolves. Read more
USDC: USDC is a dollar stablecoin issued by Circle, available on Polygon and many other networks. On Polymarket it backs pUSD, and depositing USDC is the usual way to fund an account. Read more
USDC.e: USDC.e is the older, bridged version of USDC on Polygon, distinct from native USDC. It can be wrapped into pUSD for trading on Polymarket. Read more

V

Volume: Volume is the dollar value of shares that changed hands in a market over a period, such as the past 24 hours. On Nimb's map, circle area follows volume over the chosen timeframe. Read more

W

WebSocket: A WebSocket is a connection that keeps streaming data to your browser as it changes, instead of waiting to be asked. Nimb uses Polymarket's CLOB WebSocket to stream live prices. Read more
Whale: A whale is a wallet holding a very large position in a market. Size is not skill: whales can be wrong, hedged elsewhere or market makers. Read more

Y

Yes share: A Yes share pays $1 if the outcome happens and $0 if it does not. Its price is the market's chance that the outcome happens. Read more

What are Nimb's own terms?

Four terms have one meaning across Nimb's app, docs and posts:

Market reading: working out what a prediction market's price, flow and holders say about an event, and how much to trust it.
A reading: Nimb's one-sentence summary of a market.
Read and execute: read the market in the analysis panel, then act on it in the order ticket, in one place.
Alpha: informational edge the price does not yet reflect; not a promised return, and usually smaller than it looks once fees and noise are counted.

For quick answers to common questions, see the FAQ.

Last reviewed 2026-11-07 · Data from Polymarket · Not financial advice · Nimb is not affiliated with Polymarket.