To endure.
To toughen.
A person who obtains things by force; a thug or bully.
Harsh or severe.
Difficult or demanding.
Stubborn or persistent; capable of stubbornness or persistence.
Strong and resilient; sturdy.
Undergoing plastic deformation before breaking.
Difficult to cut or chew.
Rugged or physically hardy.
Rowdy or rough.
Used to indicate lack of sympathy
Ready to do something that is not (can't be expected as) a matter of course.