Toughness

Toughness is a Fallout, Fallout 2,Fallout 3 and Fallout Tactics Perk.

Fallout, Fallout 2 and Fallout Tactics
When you are tough, you take less damage. Each level of this Perk adds +10% to your general damage resistance.

Fallout 3
With the Toughness perk, you gain +10% to overall Damage Resistance, up to the maximum of 85%.