Difficult or demanding.
Harsh or severe.
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
To endure.
To toughen.
A person who obtains things by force; a thug or bully.
Causing trouble or anxiety