Definition of double up
An double up is when we double our carpet on one hand. We will generally talk about double up in tournaments. A cash games player who doubles his stack on one move would have his opponent "stacké" more than double up. The double up is crucial and frequent in tournaments. When we have more than 10 big blinds in tournament, we will look for a situation for double up at all costs, that is to say, push our mat with a decent hand (if it is strong, it will be a plus) and hope to double our mat. If we lose the hand, we're out, but if we double up, we come back in good position in the tournament.
Using the expression double up
Expression double up is almost always used in tournaments and often during the all in before the flop. In games of cash games, winnings can be more gradual. You can go from 100 grosses blinds to 200 grosses blinds thanks to several small pools. In tournament play, since we often have less than 100 grosses blindss, we have more opportunities for double ups. If two players who have the same stack are all in preflop, one will get an double up and the other will get stacker!