What is an Overall Project Risk?
Overall project risk is the uncertainty of the project as a whole — the combined effect of all individual risks plus ambiguity, complexity, and volatility — expressed as the spread of possible outcomes, not a list of events. A project can have no scary single risk and still be very risky in aggregate; the reverse is also true.
It's managed at the strategy level: contingency sizing, approach selection (maybe agile because uncertainty is high), scope staging, and go/no-go framing. Individual risks get responses; overall risk shapes the plan itself.
Worked example
Two proposals: A has three large, well-understood risks (ground conditions, one permit, one supplier). B has no big single risk but novel technology, a new partner, three regulators, and a first-of-kind integration. A's register looks worse; B's Monte Carlo spread is twice as wide. The board prices B's overall risk with a staged commitment — fund the pilot, gate the rest — a response no individual risk entry would ever have suggested.