Related Clues:

• Heat to remove stress
• Temper, as steel
• Toughen or harden
• Indurate
• Make tough (Var.)
• Toughen, as glass
• Acclimatize (Var.)
• Make accustomed to (Var.)
• Habituate (to)
• Become accustomed to (Var.)
• Naturalize
• Accustom to hardship (Var.)
• Heat to remove stress from, as glass
• Habituate (Var.)
• Become used (to)