heart of oak

A trait said to belong to a very emotionally and/or mentally strong person. I don't know how a soldier does it—he or she must have a heart of oak. My brother has a heart of oak and has remained totally calm while coping with his wife's sudden illness.

Common Names:

Name	Pronounced	Usage
Gulnaz	-	Kazakh, Georgian, Urdu
Recep	-	Turkish
Bradford	BRAD-fərd	English
Harley	HAHR-lee	English
Ingolf	ING-gawlf (German)	Swedish, Norwegian, Danish, German
Gertrudis	-	Spanish