Describe Tom Buchanan, Why does Nick say Tom has a “cruel body”?

Tom is described as a brutal, hulking man. He is a racist, a bully, and a hypocrite. Nick describes Tom as having a cruel body, meaning that he is built for and capable of violence.

Not even the effeminate swank of his riding clothes could hide the enormous power of that body—he seemed to fill those glistening boots until he strained the top lacing and you could see a great pack of muscle shifting when his shoulder moved under his thin coat. It was a body capable of enormous leverage—a cruel body.