As an adjective badder
is (nonstandard|or|obsolete) (
bad); worse.
As a verb batter is
to hit or strike violently and repeatedly or
batter can be (architecture) to slope (of walls, buildings etc).
As a noun batter is
a beaten mixture of flour and liquid (usually egg and milk), used for baking (eg pancakes, cake, or yorkshire pudding) or to coat food (eg fish) prior to frying or
batter can be an incline on the outer face of a built wall or
batter can be (baseball) the player attempting to hit the ball with a bat.