spotter
nounUK /ˈspɒtə/
US /ˈspɑːtər/
A spotter is a person who watches carefully to help keep someone safe.
The spotter stood by the gymnast to make sure she did not fall.
OTHER MEANINGS
2. A person who looks for and finds a particular thing, like birds or trains.
My uncle is a train spotter who writes down every engine he sees.
3. A person who helps a weightlifter by watching and catching the weights if needed.
The spotter stood behind him during the heavy bench press.
4. A person who finds the exact position of something, such as an enemy or a fire.
The fire spotter climbed the tower to look for smoke in the forest.