Rover

noun

1. (usually in the plural) A randomly selected target.
2. One who roves, a wanderer, a nomad.
3. A vagabond, a tramp, an unsteady, restless person, one who by habit doesn't settle down or marry.

   "She is a rover and dislikes any sort of ties, physical or emotional."

4. A vehicle for exploring extraterrestrial bodies.
5. (Australian Rules football) A position that is one of three of a team's followers, who follow the ball around the ground. Formerly a position for short players, rovers in professional leagues are frequently over 183 cm (6').