The Great Gatsby, "bum"

Could you please tell me the precise meaning, if possible, of the word "bum" in this excerpt from the chapter IV of The Great Gatsby? Does it mean "tramp", "good-for-nothing", "worthless person" or something else?

Clarence Endive was from East Egg, as I remember. He came only once, in white knickerbockers, and had a fight with a bum named Etty in the garden.

Thank you.