Plain English Meaning
When a controller says 'ident,' they want the pilot to push the IDENT button on the transponder so the aircraft's blip flashes on their screen. This lets the controller confirm exactly which target on the radar is that aircraft.
Full Definition
A request from air traffic control for the pilot to activate the IDENT feature on the aircraft transponder, which sends a special pulse that highlights the aircraft's return on the controller's radar display for several seconds, allowing positive identification of the target.
Context Anchor
Heard in radio communication with air traffic control, especially when a controller is confirming which radar target is your aircraft.