Void / Push
A bet that is cancelled with the stake refunded: 'void' for a nullified bet, 'push' when a result lands exactly on the line.
Definition
A void (or 'no action') bet is one that is cancelled, because an event is abandoned, a player withdraws, or specific rules apply, and the stake is returned with no win or loss. A push is the specific case in point-spread and totals betting where the result falls exactly on the line (for example, a favourite of -3 wins by exactly 3), so neither side wins and stakes are refunded. Half-point lines (such as 2.5) exist precisely to avoid pushes. In a parlay, a void or pushed leg usually drops out and the parlay is recalculated on the remaining legs.
Worked example
You bet a favourite at -3 and they win 24-21, exactly 3 points. The bet pushes and your stake is refunded. Had the line been -3.5, the same result would have lost.
Why it matters
Knowing when a bet voids or pushes prevents beginners from misreading a settled slip, and it explains why bookmakers favour half-point lines that eliminate the stake-back scenario.