Someone with an intimidating and unseemly appearance and mannerisms, who treats others violently and roughly, often for hire.
"The hired thug shoved me into a locker while the rest of his crew laughed at my fear."
To commit acts of thuggery, to live the life of a thug, or to dress and act in a manner reminiscent of someone who does.
"After years of trying to shed his old image, he finally stopped dressing like a thug and started wearing clean clothes again."