Baseball betting has its own vocabulary, and a good chunk of it overlaps with the stats a broadcast throws at you. This glossary covers both: the market terms you see on a board and the pitching numbers bettors lean on. Each entry is short. Where a term has its own full page, we link to it. If you are completely new, start with how baseball betting lines are written, then come back here when a word trips you up.
Market and bet types
Moneyline
A bet on which team wins the game, with no run spread. Favorites carry a minus price (-150 means you risk $150 to win $100) and underdogs a plus price (+130 means a $100 bet wins $130).
Run line
Baseball’s version of a point spread, almost always set at 1.5 runs. The favorite at -1.5 must win by two or more; the underdog at +1.5 wins the bet by winning the game or losing by exactly one. The full breakdown is on our run line page.
Alternate run line
Any run line other than the standard 1.5, such as -2.5 or +2.5. Wider spreads change the price a lot: a favorite at -2.5 might pay plus money even when it is -200 on the moneyline.
Reverse run line
Taking the favorite at +1.5 or the underdog at -1.5, the opposite of the usual setup. The favorite at +1.5 is very likely to cover and carries a steep minus price. The underdog at -1.5 needs to win by two and pays a long plus price.
Over/under
A bet on whether the combined runs in a game land above or below a posted total, such as 8.5. Also called a total. Our over/under guide covers how totals are set and what moves them.
F5
Short for first five innings. F5 markets (moneyline, run line and total) settle on the score after five innings, which isolates the starting pitchers from the bullpens. See the first 5 innings guide.
NRFI / YRFI
No Run First Inning and Yes Run First Inning. You bet on whether either team scores in the first inning. We publish computed first-inning rates for every team on the NRFI page.
Props
Short for proposition bets: wagers on something other than the final result, like a pitcher’s strikeouts or a batter’s hits. Our prop bets guide goes through the common markets.
Total bases
A batter prop that counts bases from hits only: 1 for a single, 2 for a double, 3 for a triple, 4 for a home run. Walks and stolen bases do not count.
Hitter FS
On some betting and pick’em apps, FS stands for fantasy score, a prop on a hitter’s combined fantasy points for the game. Singles, homers, RBIs, runs, walks and steals all earn points, but the scoring table differs from app to app, so compare the rules before you compare lines.
Parlay
A single bet that combines two or more selections. Every leg has to win, and the payout multiplies. Two -110 legs pay about +264. The parlay calculator works out any combination.
Teaser
A parlay where you move the line in your favor on each leg in exchange for a lower payout. Teasers are common in football and basketball and rare in baseball, where runs are scarce and a half-run move is expensive.
Futures
Bets on outcomes decided weeks or months later: World Series winner, pennants, divisions, win totals and awards. Our MLB futures guide explains how the prices work.
Grand salami
A total on the combined runs across every game on the day’s schedule. It is a novelty market, and a single postponement can void it depending on house rules.
Team total
A total on one team’s runs only, not both. A team total of 4.5 asks whether that club scores five or more.
Pricing and settlement
Juice / vig
The book’s cut, built into the price. At -110 on both sides of a game you need to win about 52.4% of your bets to break even, and that gap above 50% is the vig.
Dime line
A line where the favorite and underdog prices are 10 cents apart, for example -150 and +140. A wider gap, like -150 and +130, means a bigger margin for the book.
Action
A setting on baseball sides and totals meaning the bet stands no matter who starts. If a starter is scratched, the odds are recalculated but the bet is not voided.
Listed pitchers
The opposite choice: your bet is only valid if both named starters take the mound. If either one is replaced, the bet is voided and your stake returned. Player props for pitchers usually have their own rule tied to that pitcher starting.
Push
A tie against the line. Your stake comes back. Half-run lines like 8.5 cannot push; whole numbers like 8 can.
Closing line
The final price before a game starts. Comparing the price you took with the closing line is one of the best ways to judge whether your bets are well timed.
Handle
The total amount of money wagered on a game, market or across a period. A big handle does not mean a line is right, only that many people bet it.
Units
A standard bet size, usually a small percentage of your bankroll. Talking in units lets bettors compare results without revealing dollar amounts.
Implied probability
The break-even win rate built into a price. -150 implies 60%, +150 implies 40%. It includes the book’s margin, so it is not a prediction.
No-vig price
The fair price of each side once the book’s margin is removed from a two-way line. -110 on both sides of a total is a fair +100 each.
Expected value (EV)
What a bet is worth on average if your win estimate is right: win probability times profit, minus loss probability times stake. Positive EV means your estimate beats the price.
Hook
The half run on a line, such as the .5 in 8.5. It removes the push and decides many tickets.
Pick’em
A game priced as even, with both sides near +100 or -110, so neither team is favored.
Bankroll
The money set aside for betting only. Units are usually sized as a small share of it.
Hedge
A bet on the other side of an open ticket to lock in some profit or cut a loss.
Bet slip
The ticket that lists your selections, price, stake and potential payout before you confirm.
Bettor slang
Chalk
The favorite. “Laying chalk” means betting a favorite at a minus price.
Sharp / square
A sharp is a bettor whose opinions tend to beat the closing line; a square bets for fun, often on favorites and overs. Books sometimes move a line when sharp money arrives but not when square money does.
Steam
A sudden, fast line move across the market, usually triggered by a large amount of respected money. Chasing steam after the move means taking the worse price.
ATS
Against the spread. In baseball it refers to a team’s record on the run line rather than straight up.
Laser
Baseball slang for a hard-hit line drive. In betting chatter you may also see it used for a play someone feels strongly about. That use is informal and varies between communities, so treat it as tone rather than a defined term.
Underdog / dog
The team the price expects to lose, shown with a plus number on the moneyline or +1.5 on the run line.
Cover
To win a bet against a spread. A -1.5 favorite covers by winning by two or more runs.
Fade
Betting against a team, a trend or a popular side.
Stats bettors use
ERA
Earned run average: earned runs allowed per nine innings. Familiar, but it is affected by defense and luck, so it can mislead over small samples.
WHIP
Walks plus hits per inning pitched. A quick measure of how many baserunners a pitcher allows. Around 1.10 is excellent, above 1.40 means frequent trouble.
K/9
Strikeouts per nine innings. Useful for strikeout props, though strikeout rate per batter faced is a cleaner measure because it is not affected by how many hitters reach base.
FIP
Fielding independent pitching. It estimates ERA from strikeouts, walks, hit batters and home runs only, the parts a pitcher controls without his fielders. A big gap between ERA and FIP often points to luck in one direction.
Pythagorean expectation
A formula that estimates a team’s expected winning percentage from runs scored and runs allowed. Teams that win far more than their run differential suggests usually drift back. Our MLB luck table applies it to every team with an exponent of 1.83.
Probable pitchers
The starters a team has announced for upcoming games. They drive most prices on the board, and the day’s list lives on our probable pitchers page.
If a term you need is missing, the calculators section explains most of the pricing math in practice, and the home page links every guide on the site.
Quality start
A start of at least six innings with three or fewer earned runs.
OPS
On-base percentage plus slugging percentage, a quick measure of a hitter’s total production. .800 is good, .900 is excellent.
Run differential
Runs scored minus runs allowed over a season. It predicts future wins better than the win-loss record does.
Times through the order
How many times a starter has faced the lineup. Hitters usually do better the third time through, which is why starters often leave around the 18th batter.
