Plain English Meaning
A drone plus everything needed to fly it: the aircraft, the controller on the ground, and the radio link that connects them. The whole setup together is the 'system.'
Full Definition
An unmanned aircraft system is the complete package required to operate an aircraft without a pilot on board: the unmanned aircraft itself, the control station used to fly it, the data link between them, and any associated equipment such as launch and recovery gear, cameras, or sensors. The system — not just the aircraft — is what is regulated and certified.
Context Anchor
Pilots may see this term in NOTAMs, , , and about drone activity near airports or along a planned .