Noticeably happy and optimistic.
Bright and pleasant.
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.
To endure.
To toughen.
Used to indicate lack of sympathy
A person who obtains things by force; a thug or bully.