Lacking sufficient power or strength.
Lacking legal authority.
Strong and resilient; sturdy.
Harsh or severe.
Difficult or demanding.
Stubborn or persistent; capable of stubbornness or persistence.
Undergoing plastic deformation before breaking.
Difficult to cut or chew.
Rugged or physically hardy.
Rowdy or rough.
Used to indicate lack of sympathy
To endure.
To toughen.
A person who obtains things by force; a thug or bully.