Ranged Combat Defense

From SFWiki

This skill aids in the characters defense (dodge) versus ranged combat weapons, including bows, guns, and the innate ranged weapons of some creatures (such as dragonfire).

Higher ranks in this skill mean that the character is less likely to be struck by a foe's attack with ranged weaponry. It does not provide any bonus versus close combat (melee) weapons of any kind.

This is generally a poor choice for starting characters, as the vagaries of defense do not show value until later in the game.