We do not currently know of any antonyms for string bet.
The noun string bet is defined as:
Action where a player first calls, bets or raises a certain amount and then adds more. It can be used to gather weakness/strength tells from opponents before deciding how many chips to add into the pot. It is not allowed in most games. To prevent string betting, player's action is considered final as soon as the player verbally states the amount they bet/raise, say for example "call" or the first chip touches the table in front of their stack/cards.
