bird dog
noun
1
a scout US, 1929.
2
in professional sports, a talent scout or a scout's associates who let him know about players who may be prospects for professional play US, 1950.
3
a person who provides information about potential victims to a thief or group of thieves US, 1977.
4
a person who solicits players for gambling, whether in a casino or a private poker game US, 1949.
5
in the used car business, either a customer who has been referred to a salesman or the person doing the referring US, 1975.
6
in a two-car police speed-monitoring unit, the car that chases down speeding cars or trucks based on radar readings in the second car US, 1971.
7
a navigational device in planes that points in the direction of a radio signal US, 1956