You can increase your defense at the expense of your accuracy.
You can choose to take a –1 penalty on melee attack rolls and combat maneuver checks to gain a +1 dodge bonus to your Armor Class. When your base attack bonus reaches +4, and every +4 thereafter, the penalty increases by –1 and the dodge bonus increases by +1. You can only choose to use this feat when you declare that you are making an attack or a full-attack action with a melee weapon. The effects of this feat last until your next turn.