spotter

plural spotters

1. A person who observes something.
2. A member of a sniper team who in addition to this function is responsible for providing additional information about targets from a different point of view.
3. climbingOne who supervises a person performing an activity, in order to help them should they be unable to complete it.

   Due to a spotter's lack of action in holding the weight when a lifter lost her balance, the lifter badly pulled some muscles.

   1981 December 12, Melissa Wills, “Moving Metal”, in Gay Community News, volume 9, number 21, page 10

4. USA person who gives directions for a crane or vehicle (that is challenging to navigate) from a different point of view to the moved load.

   Synonyms: banksman, dogman, lookout, observer, signalman

5. Dolphins of the genus Stenella, and specifically Stenella attenuata distinguished from the streaker (Stenella coeruleoalba) and the spinner (Stenella longirostris).

   Synonyms: spotted dolphin

6. hobbiesA team member responsible for communication with the driver to keep them up-to-date about on-track events, such as other nearby cars.

   Synonyms: observer

7. broadcastingA person employed to assist a sports presenter by identifying the players or events during a game.