Poker glossary
3-bet
The second raise before the flop — a re-raise of the opening raise.
Also: 3-bet, 3bet, three-bet, 3-bets
The big blind counts as the first bet, the open raise is the second, and the re-raise is the “third” bet — hence the name. A 4-bet is a re-raise of a 3-bet.
3-bet ranges typically contain strong hands for value and some hands with good blockers, like suited aces, as bluffs.