What term is used to coordinate separation action between controllers?

The term that is used to coordinate separation action between controllers is "Traffic." This term is specifically utilized in air traffic control communications to inform one controller about the presence of other aircraft nearby in relation to a specific aircraft's trajectory. It establishes awareness between controllers about traffic situations that could affect flight safety, thereby facilitating effective coordination and separation among different airspace users.

By making known the existence of certain traffic, controllers are able to execute separation actions more effectively, ensuring that aircraft maintain safe distances from each other in controlled airspace. This action is crucial for maintaining operational safety and efficiency in a busy air traffic environment.

Other terms listed, while related to air traffic control communications, do not specifically denote the coordinated action focused on separation. "Relay," for instance, pertains to the act of passing on information from one controller to another. "Alert" generally refers to notifying about a potential hazard or situation, and "Point Out" involves informing another controller about an aircraft's position or intentions, but does not specifically convey the coordination needed for separation actions.