making great mental demands; hard to comprehend or solve or believe
very difficult; severely testing stamina or resolution
someone who learned to fight in the streets rather than being formally trained in the sport of boxing
unfortunate or hard to bear
violent and lawless
physically toughened
an aggressive and violent young criminal
a cruel and brutal fellow
substantially made or constructed
feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')
not given to gentleness or sentimentality
resistant to cutting or chewing
hard volcanic rock composed of compacted volcanic ash
