Toughen/ˈtʌfn/ Definition 1 of 3Pro Tip 1/3Personal Growth Often describes personal development through challenges. Living abroad toughened her up considerably. Pro Tip 2/3Emotional Strength Can imply developing emotional resilience, not just physical. He toughened up after years of competitive sports. Pro Tip 3/3Preparedness Used for indicating readiness for difficult situations. Soldiers must toughen up before deployment.