A drifter was a person who moves from place-to-place rather than settling down.
In 2372, when Tom Paris pretended to be leaving USS Voyager to help to locate a mole in the crew, he said to Neelix that he considered himself to be a drifter. According to Paris, the life of a drifter consisted of having the "Freedom to do what you want, when you want. No rules to follow, nobody depending on you, right?" (VOY: "Investigations")