A squeeze, or to put a squeeze on somebody, or a squeeze play, means to make a large raise after there has already been one raise and at least one call. Whereas the first player ideally folds, since he's now caught between two or more opponents and doesn't know what the players after him will do, the second player and all those after him often don't have strong enough hands to call a reraise and so will fold.
Player A raises by $4.
Player B calls.
Player C raises by $20 -> he squeezes.
Prerequisites for a squeezeplayYour own image, the styles of the opposition, your relative position to them and the stack sizes are the important factors for a successful squeeze.
A trivial ground rule is that a squeeze only makes sense if the opponents can fold. On the other hand, the range of the opposition, in particular that of the open raiser, must be large enough that he could hold a hand that he would immediately discard.It makes no sense to squeeze if the opposition is very loose or the raising player only raises a few hands, so that he will seldom fold them. Furthermore, the opposition must respect your reraises.