Definition
Other aircraft detected by a traffic advisory system (such as TCAS or TIS) whose position, altitude, or projected flight path brings them close enough to the pilot's aircraft to warrant attention as potential collision threats.
Plain English
Nearby aircraft that show up on a cockpit traffic display because they are close enough to be worth watching.
Context Anchor
Seen in traffic avoidance discussions and on cockpit traffic displays that show other aircraft around you.
Derivation
Intruding' comes from the Latin intrudere, meaning 'to thrust in.' In this context it doesn't suggest hostility — just that another aircraft is entering the protected airspace around your own. 'Target' is borrowed from radar usage, where any returned signal from an object is called a target.
Why Pilots Care
Prompt recognition lets the pilot take action to maintain separation and avoid a mid-air collision.
Intuition Check
Intruding does not mean the other pilot is doing something wrong. Target does not mean something to shoot at; here it means a tracked aircraft symbol on a traffic display.
Example Sentence 1
The traffic display showed two intruding targets within five miles, both at similar altitudes.
Example Sentence 2
After leveling at cruise, the display cleared the intruding targets once they passed behind us by three miles.