Tough

someone who learned to fight in the streets rather than being formally trained in the sport of boxing

an aggressive and violent young criminal

a cruel and brutal fellow

not given to gentleness or sentimentality

very difficult

physically toughened

substantially made or constructed

violent and lawless

feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')

resistant to cutting or chewing

unfortunate or hard to bear

making great mental demands